Programs & Examples On #Cross server

How do I disable a Button in Flutter?

You can set also blank condition, in place of set null

         var isDisable=true;


              padding: const EdgeInsets.all(20),
              textColor: Colors.white,
              onPressed:  isDisable
                  ? () => (){} : myClickingData(),
              child: Text('Button'),

Create table with jQuery - append

You need to append the tr inside the table so I updated your selector inside your loop and removed the closing table because it is not necessary.

$('#here_table').append(  '<table />' );

    $('#here_table table').append( '<tr><td>' + 'result' +  i + '</td></tr>' );

The main problem was that you were appending the tr to the div here_table.

Edit: Here is a JavaScript version if performance is a concern. Using document fragment will not cause a reflow for every iteration of the loop

var doc = document;

var fragment = doc.createDocumentFragment();

for (i = 0; i < 3; i++) {
    var tr = doc.createElement("tr");

    var td = doc.createElement("td");
    td.innerHTML = "content";


    //does not trigger reflow

var table = doc.createElement("table");



Change Default branch in gitlab

In the latest GitLab Community Edition version 9.2.2.:

  1. You have to click on 'Settings' tab located at right most on tabs panel after opening the project.
  2. Under 'Settings' you will get section 'Default Branch' dropdown which will give you all branches for the repository. Select the desired branch.
  3. Scroll down to hit green colored 'Save changes' button located just after 'Project Avatar'.

Please refer image below:

enter image description here

The differences between initialize, define, declare a variable

"So does it mean definition equals declaration plus initialization."

Not necessarily, your declaration might be without any variable being initialized like:

 void helloWorld(); //declaration or Prototype.

 void helloWorld()
    std::cout << "Hello World\n";

Abstraction VS Information Hiding VS Encapsulation

Abstraction is hiding the implementation details by providing a layer over the basic functionality.

Information Hiding is hiding the data which is being affected by that implementation. Use of private and public comes under this. For example, hiding the variables of the classes.

Encapsulation is just putting all similar data and functions into a group e.g Class in programming; Packet in networking.

Through the use of Classes, we implement all three concepts - Abstraction, Information Hiding and Encapsulation

How to use Checkbox inside Select Option

You can try Bootstrap-select. It has a live search too!

How to access the services from RESTful API in my angularjs page?

Just to expand on $http (shortcut methods) here:$http

//Snippet from the page

$'/someUrl', data).success(successCallback);

//available shortcut methods


Application Crashes With "Internal Error In The .NET Runtime"

In my case the problem was a C++/CLI library in which there was a call to the NtQuerySystemInformation; for some kind of reason sometimes (and under mysterious circumstances), when it was called the CLR heap got corrupted and the application crashed.

I've resolved the problem using a "custom heap" created with HeapCreate and allocating there the buffers used by that function.

Pandas: Creating DataFrame from Series

I guess anther way, possibly faster, to achieve this is 1) Use dict comprehension to get desired dict (i.e., taking 2nd col of each array) 2) Then use pd.DataFrame to create an instance directly from the dict without loop over each col and concat.

Assuming your mat looks like this (you can ignore this since your mat is loaded from file):

In [135]: mat = {'a': np.random.randint(5, size=(4,2)),
   .....: 'b': np.random.randint(5, size=(4,2))}

In [136]: mat
{'a': array([[2, 0],
        [3, 4],
        [0, 1],
        [4, 2]]), 'b': array([[1, 0],
        [1, 1],
        [1, 0],
        [2, 1]])}

Then you can do:

In [137]: df = pd.DataFrame ({name:mat[name][:,1] for name in mat})

In [138]: df
   a  b
0  0  0
1  4  1
2  1  0
3  2  1

[4 rows x 2 columns]

Connect to sqlplus in a shell script and run SQL scripts

Some of the other answers here inspired me to write a script for automating the mixed sequential execution of SQL tasks using SQLPLUS along with shell commands for a project, a process that was previously manually done. Maybe this (highly sanitized) example will be useful to someone else:


runsql () {
  # param 1 is $1
sqlplus -S /nolog << EOF
CONNECT $1@$hoststring;
whenever sqlerror exit sql.sqlcode;
set echo off
set heading off

echo "TS::$(date): Starting SCHEM_A.PROC_YOU_NEED()..."
runsql "$acreds" "execute SCHEM_A.PROC_YOU_NEED();"

echo "TS::$(date): Starting superusefuljob..."

echo "TS::$(date): Starting SCHEM_B.SECRET_B_PROC()..."
runsql "$bcreds" "execute SCHEM_B.SECRET_B_PROC();"

echo "TS::$(date): DONE"

runsql allows you to pass a credential string as the first argument, and any SQL you need as the second argument. The variables containing the credentials are included for illustration, but for security I actually source them from another file. If you wanted to handle multiple database connections, you could easily modify the function to accept the hoststring as an additional parameter.

One line if/else condition in linux shell scripting

It's not a direct answer to the question but you could just use the OR-operator

( grep "#SystemMaxUse=" journald.conf > /dev/null && sed -i 's/\#SystemMaxUse=/SystemMaxUse=50M/g' journald.conf ) || echo "This file has been edited. You'll need to do it manually."

Transfer git repositories from GitLab to GitHub - can we, how to and pitfalls (if any)?

You can transfer those (simply by adding a remote to a GitHub repo and by pushing them)

  • create an empty repo on GitHub
  • git remote add github https://[email protected]/yourLogin/yourRepoName.git
  • git push --mirror github

The history will be the same.

But you will loose the access control (teams defined in GitLab with specific access rights on your repo)

If you facing any issue with the https URL of the GitHub repo:

The requested URL returned an error: 403

All you need to do is to enter your GitHub password, but the OP suggests:

Then you might need to push it the ssh way. You can read more on how to do it here.

See "Pushing to Git returning Error Code 403 fatal: HTTP request failed".

Spring 3 MVC accessing HttpRequest from controller

@RequestMapping(value="/") public String home(HttpServletRequest request){
    System.out.println("My Attribute :: "+request.getAttribute("YourAttributeName"));
    return "home"; 

Override using CSS

Of course the !important trick is decisive here, but targeting more specifically may help not only to have your override actually applied (weight criteria can rule over !important) but also to avoid overriding unintended elements.

With the developer tools of your browser, identify the exact value of the offending style attribute; e.g.:

"font-family: arial, helvetica, sans-serif;"


"display: block;"

Then, decide which branch of selectors you will override; you can broaden or narrow your choice to fit your needs, e.g.:

p span


section.article-into.clearfix p span

Finally, in your custom.css, use the [attribute^=value] selector and the !important declaration:

p span[style^="font-family: arial"] {
  font-family: "Times New Roman", Times, serif !important;

Note you don't have to quote the whole style attribute value, just enough to unambigously match the string.

Returning the product of a list

import operator
reduce(operator.mul, list, 1)

How to transform currentTimeMillis to a readable date format?

It will work.

long yourmilliseconds = System.currentTimeMillis();
SimpleDateFormat sdf = new SimpleDateFormat("MMM dd,yyyy HH:mm");    
Date resultdate = new Date(yourmilliseconds);

Variable length (Dynamic) Arrays in Java

Simple code for dynamic array. In below code then array will become full of size we copy all element to new double size array(variable size array).sample code is below 

public class DynamicArray {
 static   int []increaseSizeOfArray(int []arr){
          int []brr=new int[(arr.length*2)];
          for (int i = 0; i < arr.length; i++) {
          return brr;
public static void main(String[] args) {
     int []arr=new int[5];
      for (int i = 0; i < 11; i++) {
          if (i<arr.length) {
          else {

for (int i = 0; i < arr.length; i++) {


Source : How to make dynamic array

Better way to sum a property value in an array

It's working for me in TypeScript and JavaScript:

let lst = [_x000D_
     { description:'Senior', price: 10},_x000D_
     { description:'Adult', price: 20},_x000D_
     { description:'Child', price: 30}_x000D_
let sum = => o.price).reduce((a, c) => { return a + c });_x000D_

I hope is useful.

How to get the cookie value in website

add this function to your global.asax

protected void Application_AuthenticateRequest(Object sender, EventArgs e)
    string cookieName = FormsAuthentication.FormsCookieName;
    HttpCookie authCookie = Context.Request.Cookies[cookieName];

    if (authCookie == null)
    FormsAuthenticationTicket authTicket = null;
        authTicket = FormsAuthentication.Decrypt(authCookie.Value);
    if (authTicket == null)
    string[] roles = authTicket.UserData.Split(new char[] { '|' });
    FormsIdentity id = new FormsIdentity(authTicket);
    GenericPrincipal principal = new GenericPrincipal(id, roles);

    Context.User = principal;

then you can use HttpContext.Current.User.Identity.Name to get username. hope it helps

No operator matches the given name and argument type(s). You might need to add explicit type casts. -- Netbeans, Postgresql 8.4 and Glassfish

If anyone is having this exception and is building the query using Scala multi-line strings:

Looks like there is a problem with some JPA drivers in this situation. I'm not sure what is the character Scala uses for LINE END, but when you have a parameter right at the end of the line, the LINE END character seems to be attached to the parameter and so when the driver parses the query, this error comes up. A simple work around is to leave an empty space right after the param at the end:

SELECT * FROM some_table a
WHERE a.col = ?param
AND a.col2 = ?param2

So, just make sure to leave an empty space after param (and param2, if you have a line break there).

Android Studio Gradle Configuration with name 'default' not found

When i import my library manually i had same issue. I tried to add my library with file > import module and it solved my issue.

What are .a and .so files?

.a are static libraries. If you use code stored inside them, it's taken from them and embedded into your own binary. In Visual Studio, these would be .lib files.

.so are dynamic libraries. If you use code stored inside them, it's not taken and embedded into your own binary. Instead it's just referenced, so the binary will depend on them and the code from the so file is added/loaded at runtime. In Visual Studio/Windows these would be .dll files (with small .lib files containing linking information).

How do I find out which keystore was used to sign an app?

You can do this with the apksigner tool that is part of the Android SDK:

apksigner verify --print-certs my_app.apk

You can find apksigner inside the build-tools directory. For example: ~/Library/Android/sdk/build-tools/29.0.1/apksigner

Assigning more than one class for one event

    $('.tag1, .tag2').on('click', function() {

      if ($(this).hasClass('clickedTag')){
         // code here
      } else {
         // and here



function dothing() {
   if ($(this).hasClass('clickedTag')){
        // code here
    } else {
        // and here

$('.tag1, .tag2').on('click', dothing);


 $('[class^=tag]').on('click', dothing);

How to open a file / browse dialog using javascript?

Here is a non-jQuery solution. Note you can't just use .click() as some browsers do not support it.

<script type="text/javascript">
function performClick(elemId) {
   var elem = document.getElementById(elemId);
   if(elem && document.createEvent) {
      var evt = document.createEvent("MouseEvents");
      evt.initEvent("click", true, false);
<a href="#" onclick="performClick('theFile');">Open file dialog</a>
<input type="file" id="theFile" />

Exception.Message vs Exception.ToString()

Depends on the information you need. For debugging the stack trace & inner exception are useful:

    string message =
        "Exception type " + ex.GetType() + Environment.NewLine +
        "Exception message: " + ex.Message + Environment.NewLine +
        "Stack trace: " + ex.StackTrace + Environment.NewLine;
    if (ex.InnerException != null)
        message += "---BEGIN InnerException--- " + Environment.NewLine +
                   "Exception type " + ex.InnerException.GetType() + Environment.NewLine +
                   "Exception message: " + ex.InnerException.Message + Environment.NewLine +
                   "Stack trace: " + ex.InnerException.StackTrace + Environment.NewLine +
                   "---END Inner Exception";

Convert String to Type in C#

You can only use just the name of the type (with its namespace, of course) if the type is in mscorlib or the calling assembly. Otherwise, you've got to include the assembly name as well:

Type type = Type.GetType("Namespace.MyClass, MyAssembly");

If the assembly is strongly named, you've got to include all that information too. See the documentation for Type.GetType(string) for more information.

Alternatively, if you have a reference to the assembly already (e.g. through a well-known type) you can use Assembly.GetType:

Assembly asm = typeof(SomeKnownType).Assembly;
Type type = asm.GetType(namespaceQualifiedTypeName);

Django, creating a custom 500/404 error page

def handler404(request, exception):
    context = RequestContext(request)
    err_code = 404
    response = render_to_response('404.html', {"code":err_code}, context)
    response.status_code = 404
    return response

# <project_folder>
handler404 = 'todo.views.handler404' 

This works on django 2.0

Be sure to include your custom 404.html inside the app templates folder.

When to use a View instead of a Table?

Oh there are many differences you will need to consider

Views for selection:

  1. Views provide abstraction over tables. You can add/remove fields easily in a view without modifying your underlying schema
  2. Views can model complex joins easily.
  3. Views can hide database-specific stuff from you. E.g. if you need to do some checks using Oracles SYS_CONTEXT function or many other things
  4. You can easily manage your GRANTS directly on views, rather than the actual tables. It's easier to manage if you know a certain user may only access a view.
  5. Views can help you with backwards compatibility. You can change the underlying schema, but the views can hide those facts from a certain client.

Views for insertion/updates:

  1. You can handle security issues with views by using such functionality as Oracle's "WITH CHECK OPTION" clause directly in the view


  1. You lose information about relations (primary keys, foreign keys)
  2. It's not obvious whether you will be able to insert/update a view, because the view hides its underlying joins from you

iPhone system font

Category UIFontSystemFonts for UIFont (UIInterface.h) provides several convenient predefined sizes.

@interface UIFont (UIFontSystemFonts)
 + (CGFloat)labelFontSize;
 + (CGFloat)buttonFontSize;
 + (CGFloat)smallSystemFontSize;
 + (CGFloat)systemFontSize;

I use it for chat messages (labels) and it work well when I need to get size of text blocks.

 [UIFont systemFontOfSize:[UIFont labelFontSize]];

Happy coding!

Struct inheritance in C++

Yes, c++ struct is very similar to c++ class, except the fact that everything is publicly inherited, ( single / multilevel / hierarchical inheritance, but not hybrid and multiple inheritance ) here is a code for demonstration

using namespace std;

struct parent
    int data;
    parent() : data(3){};           // default constructor
    parent(int x) : data(x){};      // parameterized constructor
struct child : parent
    int a , b;
    child(): a(1) , b(2){};             // default constructor
    child(int x, int y) : a(x) , b(y){};// parameterized constructor
    child(int x, int y,int z)           // parameterized constructor
        a = x;
        b = y;
        data = z;
    child(const child &C)               // copy constructor
        a = C.a;
        b = C.b;
        data =;
int main()
   child c1 ,
         c2(10 , 20),
         c3(10 , 20, 30),

    auto print = [](const child &c) { cout<<c.a<<"\t"<<c.b<<"\t"<<<<endl; };

1       2       3
10      20      3
10      20      30
10      20      30

Converting XDocument to XmlDocument and vice versa

For me this single line solution works very well

XDocument y = XDocument.Parse(pXmldoc.OuterXml); // where pXmldoc is of type XMLDocument

Rotate a div using javascript

To rotate a DIV we can add some CSS that, well, rotates the DIV using CSS transform rotate.

To toggle the rotation we can keep a flag, a simple variable with a boolean value that tells us what way to rotate.

var rotated = false;

document.getElementById('button').onclick = function() {
    var div = document.getElementById('div'),
        deg = rotated ? 0 : 66; = 'rotate('+deg+'deg)';    = 'rotate('+deg+'deg)';     = 'rotate('+deg+'deg)';      = 'rotate('+deg+'deg)';       = 'rotate('+deg+'deg)'; 

    rotated = !rotated;

var rotated = false;_x000D_
document.getElementById('button').onclick = function() {_x000D_
    var div = document.getElementById('div'),_x000D_
        deg = rotated ? 0 : 66;_x000D_
_x000D_ = 'rotate('+deg+'deg)'; _x000D_    = 'rotate('+deg+'deg)'; _x000D_     = 'rotate('+deg+'deg)'; _x000D_      = 'rotate('+deg+'deg)'; _x000D_       = 'rotate('+deg+'deg)'; _x000D_
    rotated = !rotated;_x000D_
#div {_x000D_
    position:relative; _x000D_
    height: 200px; _x000D_
    width: 200px; _x000D_
    margin: 30px;_x000D_
    background: red;_x000D_
<button id="button">rotate</button>_x000D_
<br /><br />_x000D_
<div id="div"></div>

To add some animation to the rotation all we have to do is add CSS transitions

div {
    -webkit-transition: all 0.5s ease-in-out;
    -moz-transition: all 0.5s ease-in-out;
    -o-transition: all 0.5s ease-in-out;
    transition: all 0.5s ease-in-out;

var rotated = false;_x000D_
document.getElementById('button').onclick = function() {_x000D_
    var div = document.getElementById('div'),_x000D_
        deg = rotated ? 0 : 66;_x000D_
_x000D_ = 'rotate('+deg+'deg)'; _x000D_    = 'rotate('+deg+'deg)'; _x000D_     = 'rotate('+deg+'deg)'; _x000D_      = 'rotate('+deg+'deg)'; _x000D_       = 'rotate('+deg+'deg)'; _x000D_
    rotated = !rotated;_x000D_
#div {_x000D_
    position:relative; _x000D_
    height: 200px; _x000D_
    width: 200px; _x000D_
    margin: 30px;_x000D_
    background: red;_x000D_
    -webkit-transition: all 0.5s ease-in-out;_x000D_
    -moz-transition: all 0.5s ease-in-out;_x000D_
    -o-transition: all 0.5s ease-in-out;_x000D_
    transition: all 0.5s ease-in-out;_x000D_
<button id="button">rotate</button>_x000D_
<br /><br />_x000D_
<div id="div"></div>

Another way to do it is using classes, and setting all the styles in a stylesheet, thus keeping them out of the javascript

document.getElementById('button').onclick = function() {

document.getElementById('button').onclick = function() {_x000D_
#div {_x000D_
    position:relative; _x000D_
    height: 200px; _x000D_
    width: 200px; _x000D_
    margin: 30px;_x000D_
    background: red;_x000D_
    -webkit-transition: all 0.5s ease-in-out;_x000D_
    -moz-transition: all 0.5s ease-in-out;_x000D_
    -o-transition: all 0.5s ease-in-out;_x000D_
    transition: all 0.5s ease-in-out;_x000D_
#div.rotated {_x000D_
    -webkit-transform : rotate(66deg); _x000D_
    -moz-transform : rotate(66deg); _x000D_
    -ms-transform : rotate(66deg); _x000D_
    -o-transform : rotate(66deg); _x000D_
    transform : rotate(66deg); _x000D_
<button id="button">rotate</button>_x000D_
<br /><br />_x000D_
<div id="div"></div>

How to set tint for an image view programmatically in android?

For set tint for an image view programmatically in android

I have two methods for android :





I hope I helped anyone out :-)

XDocument or XmlDocument

I am surprised none of the answers so far mentions the fact that XmlDocument provides no line information, while XDocument does (through the IXmlLineInfo interface).

This can be a critical feature in some cases (for example if you want to report errors in an XML, or keep track of where elements are defined in general) and you better be aware of this before you happily start to implement using XmlDocument, to later discover you have to change it all.

How to create CSV Excel file C#?

If anyone would like I converted this to an extension method on IEnumerable:

public static class ListExtensions
    public static string ExportAsCSV<T>(this IEnumerable<T> listToExport, bool includeHeaderLine, string delimeter)
        StringBuilder sb = new StringBuilder();

        IList<PropertyInfo> propertyInfos = typeof(T).GetProperties();

        if (includeHeaderLine)
            foreach (PropertyInfo propertyInfo in propertyInfos)
            sb.Remove(sb.Length - 1, 1).AppendLine();

        foreach (T obj in listToExport)
            T localObject = obj;

            var line = String.Join(delimeter, propertyInfos.Select(x => SanitizeValuesForCSV(x.GetValue(localObject, null), delimeter)));


        return sb.ToString();

    private static string SanitizeValuesForCSV(object value, string delimeter)
        string output;

        if (value == null) return "";

        if (value is DateTime)
            output = ((DateTime)value).ToLongDateString();
            output = value.ToString();                

        if (output.Contains(delimeter) || output.Contains("\""))
            output = '"' + output.Replace("\"", "\"\"") + '"';

        output = output.Replace("\n", " ");
        output = output.Replace("\r", "");

        return output;

How to read file contents into a variable in a batch file?

just do:

type version.txt

and it will be displayed as if you typed:

set /p Build=<version.txt
echo %Build%

PDF Blob - Pop up window not showing content

You need to set the responseType to arraybuffer if you would like to create a blob from your response data:

$'/fetchBlobURL',{myParams}, {responseType: 'arraybuffer'})
   .success(function (data) {
       var file = new Blob([data], {type: 'application/pdf'});
       var fileURL = URL.createObjectURL(file);;

more information: Sending_and_Receiving_Binary_Data

How can I compile a Java program in Eclipse without running it?

Right click on Yourproject(in project Explorer)-->Build Project

It will compile all files in your project and updates your build folder, all without running.

When is layoutSubviews called?

have you looked at layoutIfNeeded?

The documentation snippet is below. Does the animation work if you call this method explicitly during the animation?

layoutIfNeeded Lays out the subviews if needed.

- (void)layoutIfNeeded

Discussion Use this method to force the layout of subviews before drawing.

Availability Available in iPhone OS 2.0 and later.

How to wrap async function calls into a sync function in Node.js or Javascript?

deasync turns async function into sync, implemented with a blocking mechanism by calling Node.js event loop at JavaScript layer. As a result, deasync only blocks subsequent code from running without blocking entire thread, nor incuring busy wait. With this module, here is the answer to the jsFiddle challenge:

function AnticipatedSyncFunction(){
  var ret;
      ret = "hello";
  while(ret === undefined) {
  return ret;    

var output = AnticipatedSyncFunction();
//expected: output=hello (after waiting for 3 sec)
//actual: output=hello (after waiting for 3 sec)

(disclaimer: I am the co-author of deasync. The module was created after posting this question and found no workable proposal.)

Java Process with Input/Output Stream

I think you can use thread like demon-thread for reading your input and your output reader will already be in while loop in main thread so you can read and write at same time.You can modify your program like this:

Thread T=new Thread(new Runnable() {

    public void run() {
            String input = scan.nextLine();
            input += "\n";
            try {
            } catch (IOException e) {
                // TODO Auto-generated catch block


} );

and you can reader will be same as above i.e.

while ((line = reader.readLine ()) != null) {
    System.out.println ("Stdout: " + line);

make your writer as final otherwise it wont be able to accessible by inner class.

What does "O(1) access time" mean?

O(1) means Random Access. In any Random Access Memory, the time taken to access any element at any location is the same. Here time can be any integer, but the only thing to remember is time taken to retrieve the element at (n-1)th or nth location will be same(ie constant).

Whereas O(n) is dependent on the size of n.

Finding rows that don't contain numeric data in Oracle

I've found this useful:

 select translate('your string','_0123456789','_') from dual

If the result is NULL, it's numeric (ignoring floating point numbers.)

However, I'm a bit baffled why the underscore is needed. Without it the following also returns null:

 select translate('s123','0123456789', '') from dual

There is also one of my favorite tricks - not perfect if the string contains stuff like "*" or "#":

 SELECT 'is a number' FROM dual WHERE UPPER('123') = LOWER('123')

Stop all active ajax requests in jQuery

I found it too easy for multiple requests.

step1: define a variable at top of page:

  xhrPool = []; // no need to use **var**

step2: set beforeSend in all ajax requests:

   beforeSend: function (jqXHR, settings) {

step3: use it whereever you required:

   $.each(xhrPool, function(idx, jqXHR) {

Remove CSS from a Div using JQuery

As a note, depending upon the property you may be able to set it to auto.

Java HTML Parsing

If your HTML is well-formed, you can easily employ an XML parser to do the job for you... If you're only reading, SAX would be ideal.

What is the proper declaration of main in C++?

The exact wording of the latest published standard (C++14) is:

An implementation shall allow both

  • a function of () returning int and

  • a function of (int, pointer to pointer to char) returning int

as the type of main.

This makes it clear that alternative spellings are permitted so long as the type of main is the type int() or int(int, char**). So the following are also permitted:

  • int main(void)
  • auto main() -> int
  • int main ( )
  • signed int main()
  • typedef char **a; typedef int b, e; e main(b d, a c)

UnsupportedClassVersionError unsupported major.minor version 51.0 unable to load class

java_home environment variable should point to the location of the proper version of java installation directory, so that tomcat starts with the right version. for example it you built the project with java 1.7 , then make sure that JAVA_HOME environment variable points to the jdk 1.7 installation directory in your machine.

I had same problem , when i deploy the war in tomcat and run, the link throws the error. But pointing the variable - JAVA_HOME to jdk 1.7 resolved the issue, as my war file was built in java 1.7 environment.

Searching a string in eclipse workspace

A lot of answers only explain how to do the search.

To view the results look for a search tab (normally docked at the bottom of the screen):

How to extract URL parameters from a URL with Ruby or Rails?

Check out the addressable gem - a popular replacement for Ruby's URI module that makes query parsing easy:

require "addressable/uri"
uri = Addressable::URI.parse("")
=> 'value1'

(It also apparently handles param encoding/decoding, unlike URI)

How to set the focus for a particular field in a Bootstrap modal, once it appears

Bootstrap modal show event

$('#modal-content').on('', function() {


Entity Framework Code First - two Foreign Keys from same table

You can try this too:

public class Match
    public int MatchId { get; set; }

    [ForeignKey("HomeTeam"), Column(Order = 0)]
    public int? HomeTeamId { get; set; }
    [ForeignKey("GuestTeam"), Column(Order = 1)]
    public int? GuestTeamId { get; set; }

    public float HomePoints { get; set; }
    public float GuestPoints { get; set; }
    public DateTime Date { get; set; }

    public virtual Team HomeTeam { get; set; }
    public virtual Team GuestTeam { get; set; }

When you make a FK column allow NULLS, you are breaking the cycle. Or we are just cheating the EF schema generator.

In my case, this simple modification solve the problem.

List comprehension on a nested list?

Not sure what your desired output is, but if you're using list comprehension, the order follows the order of nested loops, which you have backwards. So I got the what I think you want with:

[float(y) for x in l for y in x]

The principle is: use the same order you'd use in writing it out as nested for loops.

List comprehension with if statement

If you use sufficiently big list not in b clause will do a linear search for each of the item in a. Why not use set? Set takes iterable as parameter to create a new set object.

>>> a = ["a", "b", "c", "d", "e"]
>>> b = ["c", "d", "f", "g"]
>>> set(a).intersection(set(b))
{'c', 'd'}

How to move or copy files listed by 'find' command in unix?

find /PATH/TO/YOUR/FILES -name NAME.EXT -exec cp -rfp {} /DST_DIR \;

How to get back Lost phpMyAdmin Password, XAMPP

Hi this worked for me "/opt/lampp/xampp security" in Centos

[root@XXXXX ~]# /opt/lampp/xampp security

XAMPP: Quick security check...

XAMPP: Your XAMPP pages are secured by a password.

XAMPP: Do you want to change the password anyway? [no] yes

XAMPP: Password:

XAMPP: Password (again):

XAMPP: Password protection active. Please use 'xampp' as user name!

XAMPP: MySQL is not accessable via network. Good.

XAMPP: MySQL has a root passwort set. Fine! :)

XAMPP: The FTP password for user 'daemon' is still set to 'xampp'.

XAMPP: Do you want to change the password? [yes]

XAMPP: Password:

XAMPP: Password (again):

XAMPP: Reload ProFTPD...ok.

XAMPP: Done.

[root@XXXXX ~]#

What do 3 dots next to a parameter type mean in Java?

It's Varargs :)

The varargs short for variable-length arguments is a feature that allows the method to accept variable number of arguments (zero or more). With varargs it has become simple to create methods that need to take a variable number of arguments. The feature of variable argument has been added in Java 5.

Syntax of varargs

A vararg is secified by three ellipsis (three dots) after the data type, its general form is

return_type method_name(data_type ... variableName){

Need for varargs

Prior to Java 5, in case there was a need of variable number of arguments, there were two ways to handle it

If the max number of arguments, a method can take was small and known, then overloaded versions of the method could be created. If the maximum number of arguments a method could take was large or/and unknown then the approach was to put those arguments in an array and pass them to a method which takes array as a parameter. These 2 approaches were error-prone - constructing an array of parameters every time and difficult to maintain - as the addition of new argument may result in writing a new overloaded method.

Advantages of varargs

Offers a much simpler option. Less code as no need to write overloaded methods.

Example of varargs

public class VarargsExample {
 public void displayData(String ... values){
  System.out.println("Number of arguments passed " + values.length);
  for(String s : values){
   System.out.println(s + " ");

 public static void main(String[] args) {
  VarargsExample vObj = new VarargsExample();
  // four args
  vObj.displayData("var", "args", "are", "passed");
  //three args
  vObj.displayData("Three", "args", "passed");
  // no-arg

Number of arguments passed 4
Number of arguments passed 3
Number of arguments passed 0

It can be seen from the program that length is used here to find the number of arguments passed to the method. It is possible because varargs are implicitly passed as an array. Whatever arguments are passed as varargs are stored in an array which is referred by the name given to varargs. In this program array name is values. Also note that method is called with different number of argument, first call with four arguments, then three arguments and then with zero arguments. All these calls are handled by the same method which takes varargs.

Restriction with varargs

It is possible to have other parameters with varargs parameter in a method, however in that case, varargs parameter must be the last parameter declared by the method.

void displayValues(int a, int b, int … values) // OK
   void displayValues(int a, int b, int … values, int c) // compiler error

Another restriction with varargs is that there must be only one varargs parameter.

void displayValues(int a, int b, int … values, int … moreValues) // Compiler error

Overloading varargs Methods

It is possible to overload a method that takes varargs parameter. Varargs method can be overloaded by -

Types of its vararg parameter can be different. By adding other parameters. Example of overloading varargs method

public class OverloadingVarargsExp {
 // Method which has string vararg parameter
 public void displayData(String ... values){
  System.out.println("Number of arguments passed " + values.length);
  for(String s : values){
   System.out.println(s + " ");

 // Method which has int vararg parameter
 public void displayData(int ... values){
  System.out.println("Number of arguments passed " + values.length);
  for(int i : values){
   System.out.println(i + " ");

 // Method with int vararg and one more string parameter
 public void displayData(String a, int ... values){
  System.out.println(" a " + a);
  System.out.println("Number of arguments passed " + values.length);
  for(int i : values){
   System.out.println(i + " ");

 public static void main(String[] args) {
  OverloadingVarargsExp vObj = new OverloadingVarargsExp();
  // four string args
  vObj.displayData("var", "args", "are", "passed");

  // two int args
  vObj.displayData(10, 20);

  // One String param and two int args
  vObj.displayData("Test", 20, 30);

Number of arguments passed 4

Number of arguments passed 2

 a Test
Number of arguments passed 2

Varargs and overloading ambiguity

In some cases call may be ambiguous while we have overloaded varargs method. Let's see an example

public class OverloadingVarargsExp {
 // Method which has string vararg parameter
 public void displayData(String ... values){
  System.out.println("Number of arguments passed " + values.length);
  for(String s : values){
   System.out.println(s + " ");

 // Method which has int vararg parameter
 public void displayData(int ... values){
  System.out.println("Number of arguments passed " + values.length);
  for(int i : values){
   System.out.println(i + " ");

 public static void main(String[] args) {
  OverloadingVarargsExp vObj = new OverloadingVarargsExp();
  // four string args
  vObj.displayData("var", "args", "are", "passed");

  // two int args
  vObj.displayData(10, 20);

  // This call is ambiguous

In this program when we make a call to displayData() method without any parameter it throws error, because compiler is not sure whether this method call is for displayData(String ... values) or displayData(int ... values)

Same way if we have overloaded methods where one has the vararg method of one type and another method has one parameter and vararg parameter of the same type, then also we have the ambiguity - As Exp - displayData(int ... values) and displayData(int a, int ... values)

These two overloaded methods will always have ambiguity.

C - The %x format specifier


use 0 instead of spaces to pad a field when the width option is specified. For example, printf("%2d", 3) results in " 3", while printf("%02d", 3) results in "03".

Golang append an item to a slice

NOTICE that append generates a new slice if cap is not sufficient. @kostix's answer is correct, or you can pass slice argument by pointer!

What is the significance of url-pattern in web.xml and how to configure servlet?

url-pattern is used in web.xml to map your servlet to specific URL. Please see below xml code, similar code you may find in your web.xml configuration file.

    <servlet-name>AddPhotoServlet</servlet-name>  //servlet name
    <servlet-class>upload.AddPhotoServlet</servlet-class>  //servlet class
    <servlet-name>AddPhotoServlet</servlet-name>   //servlet name
    <url-pattern>/AddPhotoServlet</url-pattern>  //how it should appear

If you change url-pattern of AddPhotoServlet from /AddPhotoServlet to /MyUrl. Then, AddPhotoServlet servlet can be accessible by using /MyUrl. Good for the security reason, where you want to hide your actual page URL.

Java Servlet url-pattern Specification:

  1. A string beginning with a '/' character and ending with a '/*' suffix is used for path mapping.
  2. A string beginning with a '*.' prefix is used as an extension mapping.
  3. A string containing only the '/' character indicates the "default" servlet of the application. In this case the servlet path is the request URI minus the context path and the path info is null.
  4. All other strings are used for exact matches only.

Reference : Java Servlet Specification

You may also read this Basics of Java Servlet

Installing Oracle Instant Client

I was able to setup Oracle Instant Client (Basic) 11g2 and Oracle ODBC (32bit) drivers on my 32bit Windows 7 PC. Note: you'll need a 'tnsnames.ora' file because it doesn't come with one. You can Google examples and copy/paste into a text file, change the parameters for your environment.

Setting up Oracle Instant Client-Basic 11g2 (Win7 32-bit)
(I think there's another step or two if your using 64-bit)

Oracle Instant Client

  • Unzip Oracle Instant Client - Basic
  • Put contents in folder like "C:\instantclient"
  • Edit PATH evironment variable, add path to Instant Client folder to the Variable Value.
  • Add new Variable called "TNS_ADMIN" point to same folder as Instant Client.
  • I had to create a "tnsnames.ora" file because it doesn't come with one. Put it in same folder as the client.
  • reboot or use Task Manager to kill "explorer.exe" and restart it to refresh the PATH environment variables.

ODBC Drivers

  • Unzip ODBC drivers
  • Copy all files into same folder as client "C:\instantclient"
  • Use command prompt to run "odbc_install.exe" (should say it was successful)

Note: The "un-documented" things that were hanging me up where...
- All files (Client and Drivers) needed to be in the same folder (nothing in sub-folders).
- Running the ODBC driver from the command prompt will allow you to see if it installs successfully. Double-clicking the installer just flashed a box on the screen, no idea it was failing because no error dialog.

After you've done this you should be able to setup a new DSN Data Source using the Oracle ODBC driver.
-Hope this helps someone else.

How to get a Color from hexadecimal Color String

Convert that string to an int color which can be used in setBackgroundColor and setTextColor

String string = "#FFFF0000";
int color = Integer.parseInt(string.replaceFirst("^#",""), 16);

The 16 means it is hexadecimal and not your regular 0-9. The result should be the same as

int color = 0xFFFF0000;

jQuery: Check if div with certain class name exists

The best way in Javascript:

if (document.getElementsByClassName("search-box").length > 0) {
// do something

How to upload (FTP) files to server in a bash script?

use this to upload a file to a remote location

#$1 is the file name
#usage:this_script <filename>
HOST='your host'
USER="your user"

quote USER $USER
put $FILE 
exit 0

Calling a function in jQuery with click()


Let's say you want to call your function passing some args to it i.e., closeIt(1, false). Then, you should build an anonymous function and call closeIt from it.

$("#closeLink").click(function() {
    closeIt(1, false);

Python division

Make at least one of them float, then it will be float division, not integer:

>>> (20.0-10) / (100-10)

Casting the result to float is too late.

adding css file with jquery

Try doing it the other way around.

$('<link rel="stylesheet" href="css/style2.css" type="text/css" />').appendTo('head');

Recyclerview inside ScrollView not scrolling smoothly

If you are using VideoView or heavy weight widgets in your childviews keep your RecyclerView with height wrap_content inside a NestedScrollView with height match_parent Then scrolling will work smooth as perfectly as you want it.



            android:clipToPadding="false" />


Thanks Micro this was from your hint!


Selenium Webdriver move mouse to Point

Got it working with

Actions builder = new Actions(driver);
WebElement el = some element;
.moveByOffset( 10, 25 )

Polygon Drawing and Getting Coordinates with Google Map API v3

The other answers show you to create the polygons, but not how to get the coordinates...

I'm not sure the best way to do it, but heres one way.. It seems like there should be a method to get the paths from the polygon, but I can't find one, and getPath() doesn't seem to work for me. So here's a manual approach that worked for me..

Once you've finished drawing your polygon, and pass in your polygon to the overlay complete function, you can find the coordinates in the polygon.overlay.latLngs.b[0].b

google.maps.event.addListener(drawingManager, 'overlaycomplete', function(polygon) {
        $.each(polygon.overlay.latLngs.b[0].b, function(key, latlng){
            var lat = latlng.d;
            var lon = latlng.e;
            console.log(lat, lon); //do something with the coordinates

note, i'm using jquery to loop over the list of coordinates, but you can do loop however.

How to compile or convert sass / scss to css with node-sass (no Ruby)?

I picked node-sass implementer for libsass because it is based on node.js.

Installing node-sass

  • (Prerequisite) If you don't have npm, install Node.js first.
  • $ npm install -g node-sass installs node-sass globally -g.

This will hopefully install all you need, if not read libsass at the bottom.

How to use node-sass from Command line and npm scripts

General format:

$ node-sass [options] <input.scss> [output.css]
$ cat <input.scss> | node-sass > output.css


  1. $ node-sass my-styles.scss my-styles.css compiles a single file manually.
  2. $ node-sass my-sass-folder/ -o my-css-folder/ compiles all the files in a folder manually.
  3. $ node-sass -w sass/ -o css/ compiles all the files in a folder automatically whenever the source file(s) are modified. -w adds a watch for changes to the file(s).

More usefull options like 'compression' @ here. Command line is good for a quick solution, however, you can use task runners like Grunt.js or Gulp.js to automate the build process.

You can also add the above examples to npm scripts. To properly use npm scripts as an alternative to gulp read this comprehensive article @ especially read about grouping tasks.

  • If there is no package.json file in your project directory running $ npm init will create one. Use it with -y to skip the questions.
  • Add "sass": "node-sass -w sass/ -o css/" to scripts in package.json file. It should look something like this:
"scripts": {
    "test" : "bla bla bla",
    "sass": "node-sass -w sass/ -o css/"
  • $ npm run sass will compile your files.

How to use with gulp

  • $ npm install -g gulp installs Gulp globally.
  • If there is no package.json file in your project directory running $ npm init will create one. Use it with -y to skip the questions.
  • $ npm install --save-dev gulp installs Gulp locally. --save-dev adds gulp to devDependencies in package.json.
  • $ npm install gulp-sass --save-dev installs gulp-sass locally.
  • Setup gulp for your project by creating a gulpfile.js file in your project root folder with this content:
'use strict';
var gulp = require('gulp');

A basic example to transpile

Add this code to your gulpfile.js:

var gulp = require('gulp');
var sass = require('gulp-sass');
gulp.task('sass', function () {
    .pipe(sass().on('error', sass.logError))

$ gulp sass runs the above task which compiles .scss file(s) in the sass folder and generates .css file(s) in the css folder.

To make life easier, let's add a watch so we don't have to compile it manually. Add this code to your gulpfile.js:

gulp.task('sass:watch', function () {'./sass/**/*.scss', ['sass']);

All is set now! Just run the watch task:

$ gulp sass:watch

How to use with Node.js

As the name of node-sass implies, you can write your own node.js scripts for transpiling. If you are curious, check out node-sass project page.

What about libsass?

Libsass is a library that needs to be built by an implementer such as sassC or in our case node-sass. Node-sass contains a built version of libsass which it uses by default. If the build file doesn't work on your machine, it tries to build libsass for your machine. This process requires Python 2.7.x (3.x doesn't work as of today). In addition:

LibSass requires GCC 4.6+ or Clang/LLVM. If your OS is older, this version may not compile. On Windows, you need MinGW with GCC 4.6+ or VS 2013 Update 4+. It is also possible to build LibSass with Clang/LLVM on Windows.

Align image to left of text on same line - Twitter Bootstrap3

For Bootstrap 3.

<div class="paragraphs">
  <div class="row">
    <div class="col-md-4">
      <div class="content-heading clearfix media">
           <h3>Experience &nbsp </h3>
           <img class="pull-left" src="../site/img/success32.png"/>
      <p>Donec id elit non mi porta gravida at eget metus. Etiam porta sem malesuada magna mollis euismod. Donec sed odio dui.</p>

What is the javascript filename naming convention?

One possible naming convention is to use something similar to the naming scheme jQuery uses. It's not universally adopted but it is pretty common.


where the product-name + plugin pair can also represent a namespace and a module. The version and filetype are usually optional.

filetype can be something relative to how the content of the file is. Often seen are:

  • min for minified files
  • custom for custom built or modified files


  • jquery-1.4.2.min.js
  • jquery.plugin-0.1.js
  • myapp.invoice.js

PHP Date Time Current Time Add Minutes

This is an old question that seems answered, but as someone pointed out above, if you use the DateTime class and PHP < 5.3.0, you can't use the add method, but you can use modify:

$date = new DateTime();
$date->modify("+30 minutes"); //or whatever value you want

Why use String.Format?

One reason it is not preferable to write the string like 'string +"Value"+ string' is because of Localization. In cases where localization is occurring we want the localized string to be correctly formatted, which could be very different from the language being coded in.

For example we need to show the following error in different languages:

MessageBox.Show(String.Format(ErrorManager.GetError("PIDV001").Description, proposalvalue.ProposalSource)


'ErrorCollector.GetError("ERR001").ErrorDescription' returns a string like "Your ID {0} is not valid". This message must be localized in many languages. In that case we can't use + in C#. We need to follow string.format.

Is there any way to debug chrome in any IOS device

If you don't need full debugging support, you can now view JavaScript console logs directly within Chrome for iOS at chrome://inspect.

Chrome for iOS Console

Java enum - why use toString instead of name

name() is a "built-in" method of enum. It is final and you cannot change its implementation. It returns the name of enum constant as it is written, e.g. in upper case, without spaces etc.

Compare MOBILE_PHONE_NUMBER and Mobile phone number. Which version is more readable? I believe the second one. This is the difference: name() always returns MOBILE_PHONE_NUMBER, toString() may be overriden to return Mobile phone number.

How to remove elements from a generic list while iterating over it?

Select the elements you do want rather than trying to remove the elements you don't want. This is so much easier (and generally more efficient too) than removing elements.

var newSequence = (from el in list
                   where el.Something || el.AnotherThing < 0
                   select el);

I wanted to post this as a comment in response to the comment left by Michael Dillon below, but it's too long and probably useful to have in my answer anyway:

Personally, I'd never remove items one-by-one, if you do need removal, then call RemoveAll which takes a predicate and only rearranges the internal array once, whereas Remove does an Array.Copy operation for every element you remove. RemoveAll is vastly more efficient.

And when you're backwards iterating over a list, you already have the index of the element you want to remove, so it would be far more efficient to call RemoveAt, because Remove first does a traversal of the list to find the index of the element you're trying to remove, but you already know that index.

So all in all, I don't see any reason to ever call Remove in a for-loop. And ideally, if it is at all possible, use the above code to stream elements from the list as needed so no second data structure has to be created at all.

How do I sort a VARCHAR column in SQL server that contains numbers?

There are a few possible ways to do this.

One would be

    WHEN ISNUMERIC(value) = 1 THEN CONVERT(INT, value) 
    ELSE 9999999 -- or something huge

the first part of the ORDER BY converts everything to an int (with a huge value for non-numerics, to sort last) then the last part takes care of alphabetics.

Note that the performance of this query is probably at least moderately ghastly on large amounts of data.

How to rename uploaded file before saving it into a directory?

The move_uploaded_file will return false if the file was not successfully moved you can put something into your code to alert you in a log if that happens, that should help you figure out why your having trouble renaming the file

How to count the NaN values in a column in pandas DataFrame

In case you need to get the non-NA (non-None) and NA (None) counts across different groups pulled out by groupby:

gdf = df.groupby(['ColumnToGroupBy'])

def countna(x):
    return (x.isna()).sum()

gdf.agg(['count', countna, 'size'])

This returns the counts of non-NA, NA and total number of entries per group.

Adding value to input field with jQuery

$.each(obj, function(index, value) {
    $('#looking_for_job_titles').tagsinput('add', value);

Display JSON Data in HTML Table

Please use datatable if you want to get result from json object. Datatable also works in the same manner of converting the json result into table format with the facility of searchable and sortable columns automatically.

Check if a record exists in the database

try this

 public static bool CheckUserData(string phone, string config)
        string sql = @"SELECT * FROM AspNetUsers WHERE PhoneNumber = @PhoneNumber";
        using (SqlConnection conn = new SqlConnection(config)
            using (SqlCommand cmd = new SqlCommand(sql, conn))
                cmd.Parameters.AddWithValue("@PhoneNumber", phone);
                SqlDataReader reader = cmd.ExecuteReader(CommandBehavior.CloseConnection);
                if (reader.HasRows)
                    return true;  // data exist
                    return false; //data not exist

Change the color of a checked menu item in a navigation drawer

Well you can achieve this using Color State Resource. If you notice inside your NavigationView you're using


Here instead of using @color/black or @color/primary_test, use a Color State List Resource. For that, first create a new xml (e.g drawer_item.xml) inside color directory (which should be inside res directory.) If you don't have a directory named color already, create one.

Now inside drawer_item.xml do something like this

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="">
    <item android:color="checked state color" android:state_checked="true" />
    <item android:color="your default color" />

Final step would be to change your NavigationView

    app:itemIconTint="@color/drawer_item"  // notice here
    app:itemTextColor="@color/drawer_item" // and here
    app:itemBackground="@android:color/transparent"// and here for setting the background color to tranparent

Like this you can use separate Color State List Resources for IconTint, ItemTextColor, ItemBackground.

Now when you set an item as checked (either in xml or programmatically), the particular item will have different color than the unchecked ones.

Problems when trying to load a package in R due to rJava

An alternative package that you can use is readxl. This package don't require external dependencies.

How to animate the change of image in an UIImageView?

Swift 4 This is just awesome

  self.imgViewPreview.transform = CGAffineTransform(scaleX: 0, y: 0)
          UIView.animate(withDuration: 1, delay: 0, usingSpringWithDamping: 0.3, initialSpringVelocity: 0, options: .curveEaseOut, animations: {
              self.imgViewPreview.image = newImage
              self.imgViewPreview.transform = .identity
          }, completion: nil)

How to change the font and font size of an HTML input tag?

<input type ="text" id="txtComputer">



Maximum on http header values?

No, HTTP does not define any limit. However most web servers do limit size of headers they accept. For example in Apache default limit is 8KB, in IIS it's 16K. Server will return 413 Entity Too Large error if headers size exceeds that limit.

Related question: How big can a user agent string get?

How to subtract 2 hours from user's local time?

Subtract from another date object

var d = new Date();

d.setHours(d.getHours() - 2);

Easiest way to rotate by 90 degrees an image using OpenCV?

Well I was looking for some details and didn't find any example. So I am posting a transposeImage function which, I hope, will help others who are looking for a direct way to rotate 90° without losing data:

IplImage* transposeImage(IplImage* image) {

    IplImage *rotated = cvCreateImage(cvSize(image->height,image->width),   
    CvPoint2D32f center;
    float center_val = (float)((image->width)-1) / 2;
    center.x = center_val;
    center.y = center_val;
    CvMat *mapMatrix = cvCreateMat( 2, 3, CV_32FC1 );        
    cv2DRotationMatrix(center, 90, 1.0, mapMatrix);
    cvWarpAffine(image, rotated, mapMatrix, 

    return rotated;

Question : Why this?

float center_val = (float)((image->width)-1) / 2; 

Answer : Because it works :) The only center I found that doesn't translate image. Though if somebody has an explanation I would be interested.

If Cell Starts with Text String... Formula

I know this is a really old post, but I found it in searching for a solution to the same problem. I don't want a nested if-statement, and Switch is apparently newer than the version of Excel I'm using. I figured out what was going wrong with my code, so I figured I'd share here in case it helps someone else.

I remembered that VLOOKUP requires the source table to be sorted alphabetically/numerically for it to work. I was initially trying to do this...

=LOOKUP(LOWER(LEFT($T$3, 1)),  {"s","l","m"}, {-1,1,0})

and it started working when I did this...

=LOOKUP(LOWER(LEFT($T$3, 1)),  {"l","m","s"}, {1,0,-1})

I was initially thinking the last value might turn out to be a default, so I wanted the zero at the last place. That doesn't seem to be the behavior anyway, so I just put the possible matches in order, and it worked.

Edit: As a final note, I see that the example in the original post has letters in alphabetical order, but I imagine the real use case might have been different if the error was happening and the letters A, B, and C were just examples.

Download/Stream file from URL -

You could try using the DirectoryEntry class with the IIS path prefix:

using(DirectoryEntry de = new DirectoryEntry("IIS://Localhost/w3svc/1/root" + DOCUMENT_PATH))
    filePath = de.Properties["Path"].Value;

if (!File.Exists(filePath))

var fileInfo = new System.IO.FileInfo(filePath);
Response.ContentType = "application/octet-stream";
Response.AddHeader("Content-Disposition", String.Format("attachment;filename=\"{0}\"", filePath));
Response.AddHeader("Content-Length", fileInfo.Length.ToString());

Detect Android phone via Javascript / jQuery

How about this one-liner?

var isAndroid = /(android)/i.test(navigator.userAgent);

The i modifier is used to perform case-insensitive matching.

Technique taken from Cordova AdMob test project:

SQL Server Error : String or binary data would be truncated

This error is usually encountered when inserting a record in a table where one of the columns is a VARCHAR or CHAR data type and the length of the value being inserted is longer than the length of the column.

I am not satisfied how Microsoft decided to inform with this "dry" response message, without any point of where to look for the answer.

Bootstrap 3 dropdown select

If you want to achieve this just keep you dropdown button and style it like the select box. The code is here and below.

.btn {
    cursor: default;
    background-color: #FFF;
    border-radius: 4px;
    text-align: left;

.caret {
    position: absolute;
    right: 16px;
    top: 16px;

.btn-default:hover, .btn-default:focus, .btn-default:active,, .open .dropdown-toggle.btn-default {
    background-color: #FFF;    
} .dropdown-toggle {
    box-shadow: 0 1px 1px rgba(0, 0, 0, 0.075) inset, 0 0 8px rgba(102, 175, 233, 0.6)

.btn-group {width: 100%}
.dropdown-menu {width: 100%;}

To make the button work like a select box, all you need to add is this tiny javascript code:

$('.dropdown-menu a').on('click', function(){    
    $('.dropdown-toggle').html($(this).html() + '<span class="caret"></span>');    

If you have multiple custom dropdowns like this you can use this javascript code:

$('.dropdown-menu a').on('click', function(){    
    $(this).parent().parent().prev().html($(this).html() + '<span class="caret"></span>');    

php variable in html no other way than: <?php echo $var; ?>

I really think you should adopt Smarty template engine as a standard php lib for your projects.

Name: {$name|capitalize}<br>

bower proxy configuration

There is no way to configure an exclusion to the proxy settings, but a colleague of mine had an create solution for that particular problem. He installed a local proxy server called cntlm. That server supports ntlm authentication and exclusions to the general proxy settings. A perfect match.

What is the difference between CloseableHttpClient and HttpClient in Apache HttpClient API?

In the next major version of the library HttpClient interface is going to extend Closeable. Until then it is recommended to use CloseableHttpClient if compatibility with earlier 4.x versions (4.0, 4.1 and 4.2) is not required.

WebSocket with SSL

To support the answer by @oberstet, if the cert is not trusted by the browser (for example you get a "this site is not secure, do you want to continue?") one solution is to open the browser options, navigate to the certificates settings and add the host and post that the websocket server is being served from to the certificate provider as an exception.

for example add '' as an exception to 'Certificate Provider Ltd'.

In firefox, this can be done from 'about:preferences' and searching for 'Certificates'

How to do a recursive find/replace of a string with awk or sed?

#!/usr/local/bin/bash -x

find * /home/www -type f | while read files

sedtest=$(sed -n '/^/,/$/p' "${files}" | sed -n '/subdomainA/p')

    if [ "${sedtest}" ]
    sed s'/subdomainA/subdomainB/'g "${files}" > "${files}".tmp
    mv "${files}".tmp "${files}"


Storing a file in a database as opposed to the file system?

Not to be vague or anything but I think the type of 'file' you will be storing is one of the biggest determining factors. If you essentially talking about a large text field which could be stored as file my preference would be for db storage.

C# int to byte[]

using static System.Console;

namespace IntToBits
    class Program
        static void Main()
            while (true)
                string s = Console.ReadLine();
                uint i;
                bool b = UInt32.TryParse(s, out i);
                if (b) IntPrinter(i);

        static void IntPrinter(uint i)
            int[] iarr = new int [32];
            for (int j = 0; j < 32; j++)
                uint tmp = i & (uint)Math.Pow(2, j);

                iarr[j] = (int)(tmp >> j);
            for (int j = 32; j > 0; j--)
                if(j%8==0 && j != 32)Write("|");
                if(j%4==0 && j%8 !=0) Write("'");

How to import data from one sheet to another

Saw this thread while looking for something else and I know it is super old, but I wanted to add my 2 cents.

NEVER USE VLOOKUP. It's one of the worst performing formulas in excel. Use index match instead. It even works without sorting data, unless you have a -1 or 1 in the end of the match formula (explained more below)

Here is a link with the appropriate formulas.

The Sheet 2 formula would be this: =IF(A2="","",INDEX(Sheet1!B:B,MATCH($A2,Sheet1!$A:$A,0)))

  • IF(A2="","", means if A2 is blank, return a blank value
  • INDEX(Sheet1!B:B, is saying INDEX B:B where B:B is the data you want to return. IE the name column.
  • Match(A2, is saying to Match A2 which is the ID you want to return the Name for.
  • Sheet1!A:A, is saying you want to match A2 to the ID column in the previous sheet
  • ,0)) is specifying you want an exact value. 0 means return an exact match to A2, -1 means return smallest value greater than or equal to A2, 1 means return the largest value that is less than or equal to A2. Keep in mind -1 and 1 have to be sorted.

More information on the Index/Match formula

Other fun facts: $ means absolute in a formula. So if you specify $B$1 when filling a formula down or over keeps that same value. If you over $B1, the B remains the same across the formula, but if you fill down, the 1 increases with the row count. Likewise, if you used B$1, filling to the right will increment the B, but keep the reference of row 1.

I also included the use of indirect in the second section. What indirect does is allow you to use the text of another cell in a formula. Since I created a named range sheet1!A:A = ID, sheet1!B:B = Name, and sheet1!C:C=Price, I can use the column name to have the exact same formula, but it uses the column heading to change the search criteria.

Good luck! Hope this helps.

Can I use a :before or :after pseudo-element on an input field?

Pseudo elements like :after, :before are only for container elements. Elements starting and closing in a single place like <input/>, <img> etc are not container elements and hence pseudo elements are not supported. Once you apply a pseudo element to container element like <div> and if you inspect the code(see the image) you can understand what I mean. Actually the pseudo element is created inside the container element. This is not possible in case of <input> or <img>

enter image description here

SQL Server Installation - What is the Installation Media Folder?

For SQL Server 2017

Download and run the installer, you are given 3 options:

  1. Basic
  2. Custom
  3. Download Media <- pick this one!

    • Select Language
    • Select ISO
    • Set download location
    • Click download
    • Exit installer once finished
  4. Extract ISO using your preferred archive utility or mount

Verify ImageMagick installation

Try this one-shot solution that should figure out where ImageMagick is, if you have access to it...

This found all versions on my Godaddy hosting.

Upload this file to your server and call it ImageMagick.php or something then run it. You will get all the info you need... hopefully...

Good luck.

// This file will run a test on your server to determine the location and versions of ImageMagick. 
//It will look in the most commonly found locations. The last two are where most popular hosts (including "Godaddy") install ImageMagick.
// Upload this script to your server and run it for a breakdown of where ImageMagick is.
echo '<h2>Test for versions and locations of ImageMagick</h2>';
echo '<b>Path: </b> convert<br>';

function alist ($array) {  //This function prints a text array as an html list.
    $alist = "<ul>";
    for ($i = 0; $i < sizeof($array); $i++) {
        $alist .= "<li>$array[$i]";
    $alist .= "</ul>";
    return $alist;

exec("convert -version", $out, $rcode); //Try to get ImageMagick "convert" program version number.
echo "Version return code is $rcode <br>"; //Print the return code: 0 if OK, nonzero if error.
echo alist($out); //Print the output of "convert -version"
echo '<br>';
echo '<b>This should test for ImageMagick version 5.x</b><br>';
echo '<b>Path: </b> /usr/bin/convert<br>';

exec("/usr/bin/convert -version", $out, $rcode); //Try to get ImageMagick "convert" program version number.
echo "Version return code is $rcode <br>"; //Print the return code: 0 if OK, nonzero if error.
echo alist($out); //Print the output of "convert -version"

echo '<br>';
echo '<b>This should test for ImageMagick version 6.x</b><br>';
echo '<b>Path: </b> /usr/local/bin/convert<br>';

exec("/usr/local/bin/convert -version", $out, $rcode); //Try to get ImageMagick "convert" program version number.
echo "Version return code is $rcode <br>"; //Print the return code: 0 if OK, nonzero if error.
echo alist($out); //Print the output of "convert -version";


Pass Hidden parameters using response.sendRedirect()

Using session, I successfully passed a parameter (name) from servlet #1 to servlet #2, using response.sendRedirect in servlet #1. Servlet #1 code:

protected void doPost(HttpServletRequest request, HttpServletResponse response) {
    String name = request.getParameter("name");
    String password = request.getParameter("password");
    request.getSession().setAttribute("name", name);

In Servlet #2, you don't need to get name back. It's already connected to the session. You could do String name = (String) request.getSession().getAttribute("name"); ---but you don't need this.

If Servlet #2 calls a JSP, you can show name this way on the JSP webpage:

<h1>Welcome ${name}</h1>

PostgreSQL 'NOT IN' and subquery

When using NOT IN, you should also consider NOT EXISTS, which handles the null cases silently. See also PostgreSQL Wiki

SELECT mac, creation_date 
FROM logs lo
WHERE logs_type_id=11
  FROM consols nx
  WHERE nx.mac = lo.mac

Maximum packet size for a TCP connection

Generally, this will be dependent on the interface the connection is using. You can probably use an ioctl() to get the MTU, and if it is ethernet, you can usually get the maximum packet size by subtracting the size of the hardware header from that, which is 14 for ethernet with no VLAN.

This is only the case if the MTU is at least that large across the network. TCP may use path MTU discovery to reduce your effective MTU.

The question is, why do you care?

SQL: Group by minimum value in one field while selecting distinct rows

If record_date has no duplicates within a group:

think of it as of filtering. Simpliy get (WHERE) one (MIN(record_date)) row from the current group:

SELECT * FROM t t1 WHERE record_date = (
                                 select MIN(record_date)
                                 from t t2 where t2.group_id = t1.group_id)

If there could be 2+ min record_date within a group:

  1. filter out non-min rows (see above)

  2. then (AND) pick only one from the 2+ min record_date rows, within the given group_id. E.g. pick the one with the min unique key:

                    AND key_id = (select MIN(key_id)
                                  from t t3 where t3.record_date = t1.record_date
                                              and t3.group_id    = t1.group_id)


key_id | group_id | record_date | other_cols
1      | 18       | 2011-04-03  | x
4      | 19       | 2009-06-01  | a
8      | 19       | 2009-06-01  | e

will select key_ids: #1 and #4

How do I access command line arguments in Python?

Python tutorial explains it:

import sys


More specifically, if you run python one two three:

>>> import sys
>>> print(sys.argv)
['', 'one', 'two', 'three']

How to check file MIME type with javascript before upload?

As Drake states this could be done with FileReader. However, what I present here is a functional version. Take in consideration that the big problem with doing this with JavaScript is to reset the input file. Well, this restricts to only JPG (for other formats you will have to change the mime type and the magic number):

<form id="form-id">
  <input type="file" id="input-id" accept="image/jpeg"/>

<script type="text/javascript">
        $("#input-id").on('change', function(event) {
            var file =[0];
            if(file.size>=2*1024*1024) {
                alert("JPG images of maximum 2MB");
                $("#form-id").get(0).reset(); //the tricky part is to "empty" the input file here I reset the form.

            if(!file.type.match('image/jp.*')) {
                alert("only JPG images");
                $("#form-id").get(0).reset(); //the tricky part is to "empty" the input file here I reset the form.

            var fileReader = new FileReader();
            fileReader.onload = function(e) {
                var int32View = new Uint8Array(;
                //verify the magic number
                // for JPG is 0xFF 0xD8 0xFF 0xE0 (see
                if(int32View.length>4 && int32View[0]==0xFF && int32View[1]==0xD8 && int32View[2]==0xFF && int32View[3]==0xE0) {
                } else {
                    alert("only valid JPG images");
                    $("#form-id").get(0).reset(); //the tricky part is to "empty" the input file here I reset the form.

Take in consideration that this was tested on latest versions of Firefox and Chrome, and on IExplore 10.

For a complete list of mime types see Wikipedia.

For a complete list of magic number see Wikipedia.

How to get current moment in ISO 8601 format with date, hour, and minute?

Still, joda-time does only support the extended format: "2015-12-09T00:22:42.930Z" not the basic: "20151209T002242.930Z" ...we might be better off testing a list of formats with java SimpleDateFormat.

Python Database connection Close

You can wrap the whole connection in a context manager, like the following:

from contextlib import contextmanager
import pyodbc
import sys

def open_db_connection(connection_string, commit=False):
    connection = pyodbc.connect(connection_string)
    cursor = connection.cursor()
        yield cursor
    except pyodbc.DatabaseError as err:
        error, = err.args
        raise err
        if commit:

Then do something like this where ever you need a database connection:

with open_db_connection("...") as cursor:
    # Your code here

The connection will close when you leave the with block. This will also rollback the transaction if an exception occurs or if you didn't open the block using with open_db_connection("...", commit=True).

How to store token in Local or Session Storage in Angular 2?

Here is the best practice:

I was use it in AngularJs, now with Angular2. Wery usefull.

Java: How to insert CLOB into oracle database

Take a look at the LobBasicSample for an example to use CLOB, BLOB, NLOB datatypes.

Sleep function in C++

The simplest way I found for C++ 11 was this:

Your includes:

#include <chrono>
#include <thread>

Your code (this is an example for sleep 1000 millisecond):

std::chrono::duration<int, std::milli> timespan(1000);

The duration could be configured to any of the following:

std::chrono::nanoseconds   duration</*signed integer type of at least 64 bits*/, std::nano>
std::chrono::microseconds  duration</*signed integer type of at least 55 bits*/, std::micro>
std::chrono::milliseconds  duration</*signed integer type of at least 45 bits*/, std::milli>
std::chrono::seconds       duration</*signed integer type of at least 35 bits*/, std::ratio<1>>  
std::chrono::minutes       duration</*signed integer type of at least 29 bits*/, std::ratio<60>>
std::chrono::hours         duration</*signed integer type of at least 23 bits*/, std::ratio<3600>>

Scanner vs. BufferedReader

In currently latest JDK6 release/build (b27), the Scanner has a smaller buffer (1024 chars) as opposed to the BufferedReader (8192 chars), but it's more than sufficient.

As to the choice, use the Scanner if you want to parse the file, use the BufferedReader if you want to read the file line by line. Also see the introductory text of their aforelinked API documentations.

  • Parsing = interpreting the given input as tokens (parts). It's able to give back you specific parts directly as int, string, decimal, etc. See also all those nextXxx() methods in Scanner class.
  • Reading = dumb streaming. It keeps giving back you all characters, which you in turn have to manually inspect if you'd like to match or compose something useful. But if you don't need to do that anyway, then reading is sufficient.

Error message Strict standards: Non-static method should not be called statically in php

Your methods are missing the static keyword. Change

function getInstanceByName($name=''){


public static function getInstanceByName($name=''){

if you want to call them statically.

Note that static methods (and Singletons) are death to testability.

Also note that you are doing way too much work in the constructor, especially all that querying shouldn't be in there. All your constructor is supposed to do is set the object into a valid state. If you have to have data from outside the class to do that consider injecting it instead of pulling it. Also note that constructors cannot return anything. They will always return void so all these return false statements do nothing but end the construction.

AngularJS not detecting Access-Control-Allow-Origin header?

It's a bug in chrome for local dev. Try other browser. Then it'll work.

Unknown column in 'field list' error on MySQL Update query

While working on a .Net app build with EF code first, I got this error message when trying to apply my migration where I had a Sql("UPDATE tableName SET columnName = value"); statement.

Turns out I misspelled the columnName.

How to create hyperlink to call phone number on mobile devices?

I also found this format online, and used it. Seems to work with or without dashes. I have verified it works on my Mac (tries to call the number in FaceTime), and on my iPhone:

<!-- Cross-platform compatible (Android + iPhone) -->
<a href="tel://1-555-555-5555">+1 (555) 555-5555</a>

SyntaxError: multiple statements found while compiling a single statement

A (partial) practical work-around is to put things into a throw-away function.


x = 1
x += 1

results in

>>> x = 1
x += 1
  File "<stdin>", line 1
    x += 1

SyntaxError: multiple statements found while compiling a single statement

However, pasting

def abc():
  x = 1
  x += 1


>>> def abc():
  x = 1
  x += 1
>>> abc()

Of course, this is OK for a quick one-off, won't work for everything you might want to do, etc. But then, going to ipython / jupyter qtconsole is probably the next simplest option.

FileNotFoundError: [Errno 2] No such file or directory

For people who are still getting error despite of passing absolute path, should check that if file has a valid name. For me I was trying to create a file with '/' in the file name. As soon as I removed '/', I was able to create the file.

Android WebView progress bar

For a horizontal progress bar, you first need to define your progress bar and link it with your XML file like this, in the onCreate:

final TextView txtview = (TextView)findViewById(;
final ProgressBar pbar = (ProgressBar) findViewById(;

Then, you may use onProgressChanged Method in your WebChromeClient:

MyView.setWebChromeClient(new WebChromeClient() {
            public void onProgressChanged(WebView view, int progress) {
               if(progress < 100 && pbar.getVisibility() == ProgressBar.GONE){

               if(progress == 100) {

After that, in your layout you have something like this

<TextView android:text="Loading, . . ." 
    android:id="@+id/tV1" android:layout_height="wrap_content"

<ProgressBar android:id="@+id/pB1"
    style="?android:attr/progressBarStyleHorizontal" android:layout_width="fill_parent"
    android:layout_height="wrap_content" android:layout_centerVertical="true"

This is how I did it in my app.

How to pass parameters to the DbContext.Database.ExecuteSqlCommand method?

Stored procedures can be executed like below

 string cmd = Constants.StoredProcs.usp_AddRoles.ToString() + " @userId, @roleIdList";
                        int result = db.Database
                                           new SqlParameter("@userId", userId),
                                           new SqlParameter("@roleIdList", roleId)

Sending files using POST with HttpURLConnection

I found using okHttp a lot easier as I could not get any of these solutions to work:

android studio 0.4.2: Gradle project sync failed error

For those who are upgrading to v1.0 of Android Studio and see the error Gradle DSL method not found: 'runProguard', If you are using version 0.14.0 or higher of the gradle plugin, you should replace "runProguard" with "minifyEnabled" in your build.gradle files. i.e.

buildTypes {
    release {
        minifyEnabled false
        proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.txt'

How do you do dynamic / dependent drop downs in Google Sheets?

Edit: The answer below may be satisfactory, but it has some drawbacks:

  1. There is a noticeable pause for the running of the script. I'm on a 160 ms latency, and it's enough to be annoying.

  2. It works by building a new range each time you edit a given row. This gives an 'invalid contents' to previous entries some of the time

I hope others can clean this up somewhat.

Here's another way to do it, that saves you a ton of range naming:

Three sheets in the worksheet: call them Main, List, and DRange (for dynamic range.) On the Main sheet, column 1 contains a timestamp. This time stamp is modified onEdit.

On List your categories and subcategories are arranged as a simple list. I'm using this for plant inventory at my tree farm, so my list looks like this:

Group   | Genus | Bot_Name
Conifer | Abies | Abies balsamea
Conifer | Abies | Abies concolor
Conifer | Abies | Abies lasiocarpa var bifolia
Conifer | Pinus | Pinus ponderosa
Conifer | Pinus | Pinus sylvestris
Conifer | Pinus | Pinus banksiana
Conifer | Pinus | Pinus cembra
Conifer | Picea | Picea pungens
Conifer | Picea | Picea glauca
Deciduous | Acer | Acer ginnala
Deciduous | Acer | Acer negundo
Deciduous | Salix | Salix discolor
Deciduous | Salix | Salix fragilis

Where | indicates separation into columns.
For convenience I also used the headers as names for named ranges.

DRrange A1 has the formula


This returns the most recent timestamp.

A2 to A4 have variations on:


with the 2 being incremented for each cell to the right.

On running A2 to A4 will have the currently selected Group, Genus and Species.

Below each of these, is a filter command something like this:


These filters will populate a block below with matching entries to the contents of the top cell.

The filters can be modified to suit your needs, and to the format of your list.

Back to Main: Data validation in Main is done using ranges from DRange.

The script I use:

function onEdit(event) {

  var dynamicSheet='DRange'; //sheet where the dynamic range lives
  var tsheet = 'Main'; //the sheet you are monitoring for edits
  var lcol = 2; //left-most column number you are monitoring; A=1, B=2 etc
  var rcol = 5; //right-most column number you are monitoring
  var tcol = 1; //column number in which you wish to populate the timestamp

  var s = event.source.getActiveSheet();
  var sname = s.getName();
  if (sname == tsheet) {
    var r = event.source.getActiveRange();
    var scol = r.getColumn();  //scol is the column number of the edited cell
    if (scol >= lcol && scol <= rcol) {
      s.getRange(r.getRow(), tcol).setValue(new Date());
      for(var looper=scol+1; looper<=rcol; looper++) {
         s.getRange(r.getRow(),looper).setValue(""); //After edit clear the entries to the right

Original Youtube presentation that gave me most of the onEdit timestamp component:

How to reenable event.preventDefault?

$('form').submit( function(e){


     //later you decide you want to submit
     $(this).trigger('submit');     or     $(this).trigger('anyEvent');

Angular 5 Service to read local .json file

Assumes, you have a data.json file in the src/app folder of your project with the following values:

        "id": 1,
        "name": "Licensed Frozen Hat",
        "description": "Incidunt et magni est ut.",
        "price": "170.00",
        "imageUrl": "",
        "quantity": 56840

3 Methods for Reading Local JSON Files

Method 1: Reading Local JSON Files Using TypeScript 2.9+ import Statement

import { Component, OnInit } from '@angular/core';
import * as data from './data.json';

  selector: 'app-root',
  template: `<ul>
      <li *ngFor="let product of products">

  styleUrls: ['./app.component.css']
export class AppComponent implements OnInit {
  title = 'Angular Example';

  products: any = (data as any).default;


Method 2: Reading Local JSON Files Using Angular HttpClient

import { Component, OnInit } from '@angular/core';
import { HttpClient } from "@angular/common/http";

  selector: 'app-root',
  template: `<ul>
      <li *ngFor="let product of products">

  styleUrls: ['./app.component.css']
export class AppComponent implements OnInit {
  title = 'Angular Example';
  products: any = [];

  constructor(private httpClient: HttpClient){}
    this.httpClient.get("assets/data.json").subscribe(data =>{
      this.products = data;

Method 3: Reading Local JSON Files in Offline Angular Apps Using ES6+ import Statement

If your Angular application goes offline, reading the JSON file with HttpClient will fail. In this case, we have one more method to import local JSON files using the ES6+ import statement which supports importing JSON files.

But first we need to add a typing file as follows:

declare module "*.json" {
  const value: any;
  export default value;

Add this inside a new file json-typings.d.ts file in the src/app folder.

Now, you can import JSON files just like TypeScript 2.9+.

import * as data from "data.json";

Trigger event on body load complete js/jquery

$(document).ready(function() {
    // do needed things

This will trigger once the DOM structure is ready.

What does double question mark (??) operator mean in PHP

It's the "null coalescing operator", added in php 7.0. The definition of how it works is:

It returns its first operand if it exists and is not NULL; otherwise it returns its second operand.

So it's actually just isset() in a handy operator.

Those two are equivalent1:

$foo = $bar ?? 'something';
$foo = isset($bar) ? $bar : 'something';


In the list of new PHP7 features:

And original RFC

EDIT: As this answer gets a lot of views, little clarification:

1There is a difference: In case of ??, the first expression is evaluated only once, as opposed to ? :, where the expression is first evaluated in the condition section, then the second time in the "answer" section.

SQL query to check if a name begins and ends with a vowel

You can try one simple solution for MySQL:

SELECT DISTINCT city FROM station WHERE city REGEXP "^[aeiou].*[aeiou]$";

Clear image on picturebox

I've had a stubborn image too, that wouldn't go away by setting the Image and InitialImage to null. To remove the image from the pictureBox for good, I had to use the code below, by calling Application.DoEvents() repeatedly:

            if (_pictureBox.Image != null)
            _pictureBox.Image = null;
            if (_pictureBox.InitialImage != null)
            _pictureBox.InitialImage = null;

invalid new-expression of abstract class type

If you use C++11, you can use the specifier "override", and it will give you a compiler error if your aren't correctly overriding an abstract method. You probably have a method that doesn't match exactly with an abstract method in the base class, so your aren't actually overriding it.

Eloquent ORM laravel 5 Get Array of ids

From a Collection, another way you could do it would be:


This will return an indexed array, perfectly usable by laravel in a whereIn() query, for instance.

How to input a path with a white space?

Use one of these threee variants:

SOME_PATH="/mnt/someProject/some path"
SOME_PATH='/mnt/someProject/some path'
SOME_PATH=/mnt/someProject/some\ path

How to print the values of slices

If you just want to see the values of an array without brackets, you can use a combination of fmt.Sprint() and strings.Trim()

a := []string{"a", "b"}
fmt.Print(strings.Trim(fmt.Sprint(a), "[]"))


a b
[a b]

Be aware though that with this solution any leading brackets will be lost from the first value and any trailing brackets will be lost from the last value

a := []string{"[a]", "[b]"}
fmt.Print(strings.Trim(fmt.Sprint(a), "[]")


a] [b
[[a] [b]]

For more info see the documentation for strings.Trim()

How to select min and max values of a column in a datatable?

var min = dt.AsEnumerable().Min(row => row["AccountLevel"]);
var max = dt.AsEnumerable().Max(row => row["AccountLevel"]);

The model item passed into the dictionary is of type .. but this dictionary requires a model item of type

The error means that you're navigating to a view whose model is declared as typeof Foo (by using @model Foo), but you actually passed it a model which is typeof Bar (note the term dictionary is used because a model is passed to the view via a ViewDataDictionary).

The error can be caused by

Passing the wrong model from a controller method to a view (or partial view)

Common examples include using a query that creates an anonymous object (or collection of anonymous objects) and passing it to the view

var model = db.Foos.Select(x => new
    ID = x.ID,
    Name = x.Name
return View(model); // passes an anonymous object to a view declared with @model Foo

or passing a collection of objects to a view that expect a single object

var model = db.Foos.Where(x => x.ID == id);
return View(model); // passes IEnumerable<Foo> to a view declared with @model Foo

The error can be easily identified at compile time by explicitly declaring the model type in the controller to match the model in the view rather than using var.

Passing the wrong model from a view to a partial view

Given the following model

public class Foo
    public Bar MyBar { get; set; }

and a main view declared with @model Foo and a partial view declared with @model Bar, then

Foo model = db.Foos.Where(x => x.ID == id).Include(x => x.Bar).FirstOrDefault();
return View(model);

will return the correct model to the main view. However the exception will be thrown if the view includes

@Html.Partial("_Bar") // or @{ Html.RenderPartial("_Bar"); }

By default, the model passed to the partial view is the model declared in the main view and you need to use

@Html.Partial("_Bar", Model.MyBar) // or @{ Html.RenderPartial("_Bar", Model.MyBar); }

to pass the instance of Bar to the partial view. Note also that if the value of MyBar is null (has not been initialized), then by default Foo will be passed to the partial, in which case, it needs to be

@Html.Partial("_Bar", new Bar())

Declaring a model in a layout

If a layout file includes a model declaration, then all views that use that layout must declare the same model, or a model that derives from that model.

If you want to include the html for a separate model in a Layout, then in the Layout, use @Html.Action(...) to call a [ChildActionOnly] method initializes that model and returns a partial view for it.

Creating a left-arrow button (like UINavigationBar's "back" style) on a UIToolbar

The Unicode Method

I think it is much easier to just use a unicode character to get the job done. You can look through arrows by googling either Unicode Triangles or Unicode Arrows. Starting with iOS6 Apple changed the character to be an emoji character with a border. To disable the border I add the 0xFE0E Unicode Variation Selector.


UIBarButtonItem *backBarButtonItem = [[UIBarButtonItem alloc] initWithTitle:backArrowString style:UIBarButtonItemStylePlain target:nil action:nil];
self.navigationItem.leftButtonItem = backBarButtonItem;

The code block is just for the demo. It would work in any button that accepts an NSString.

For a full list of characters search Google for Unicode character and what you want. Here is the entry for Black Left-Pointing Triangle.


The result

Event when window.location.href changes

You can't avoid polling, there isn't any event for href change.

Using intervals is quite light anyways if you don't go overboard. Checking the href every 50ms or so will not have any significant effect on performance if you're worried about that.

Convert varchar to float IF ISNUMERIC

..extending Mikaels' answers

  • Two data types requires two columns
  • Adding e0 fixes some ISNUMERIC issues (such as + - . and empty string being accepted)

Using a different font with twitter bootstrap

First of all you have to include your font in your website (or your CSS, to be more specific) using an appropriate @font-face rule.
From here on there are multiple ways to proceed. One thing I would not do is to edit the bootstrap.css directly - since once you get a newer version your changes will be lost. You do however have the possibility to customize your bootstrap files (there's a customize page on their website). Just enter the name of your font with all the fallback names into the corresponding typography textbox. Of course you will have to do this whenever you get a new or updated version of your bootstrap files.
Another chance you have is to overwrite the bootstrap rules within a different stylesheet. If you do this you just have to use selectors that are as specific as (or more specific than) the bootstrap selectors.
Side note: If you care about browser support a single EOT version of your font might not be sufficient. See for a support table.

MySql: is it possible to 'SUM IF' or to 'COUNT IF'?

There is a slight difference between the top answers, namely SUM(case when kind = 1 then 1 else 0 end) and SUM(kind=1).

When all values in column kind happen to be NULL, the result of SUM(case when kind = 1 then 1 else 0 end) is 0, whereas the result of SUM(kind=1) is NULL.

An example (!9/b23807/2):


(`first_col` int, `second_col` int)

    (`first_col`, `second_col`)
       (1, NULL),
       (1, NULL),
       (NULL, NULL)

Query results:

SELECT SUM(first_col=1) FROM Table1;
-- Result: 2
SELECT SUM(first_col=2) FROM Table1;
-- Result: 0
SELECT SUM(second_col=1) FROM Table1;
-- Result: NULL
-- Result: 0

How do I handle too long index names in a Ruby on Rails ActiveRecord migration?

Provide the :name option to add_index, e.g.:

add_index :studies,
  ["user_id", "university_id", "subject_name_id", "subject_type_id"], 
  unique: true,
  name: 'my_index'

If using the :index option on references in a create_table block, it takes the same options hash as add_index as its value:

t.references :long_name, index: { name: :my_index }

Python List & for-each access (Find/Replace in built-in list)

Python is not Java, nor C/C++ -- you need to stop thinking that way to really utilize the power of Python.

Python does not have pass-by-value, nor pass-by-reference, but instead uses pass-by-name (or pass-by-object) -- in other words, nearly everything is bound to a name that you can then use (the two obvious exceptions being tuple- and list-indexing).

When you do spam = "green", you have bound the name spam to the string object "green"; if you then do eggs = spam you have not copied anything, you have not made reference pointers; you have simply bound another name, eggs, to the same object ("green" in this case). If you then bind spam to something else (spam = 3.14159) eggs will still be bound to "green".

When a for-loop executes, it takes the name you give it, and binds it in turn to each object in the iterable while running the loop; when you call a function, it takes the names in the function header and binds them to the arguments passed; reassigning a name is actually rebinding a name (it can take a while to absorb this -- it did for me, anyway).

With for-loops utilizing lists, there are two basic ways to assign back to the list:

for i, item in enumerate(some_list):
    some_list[i] = process(item)


new_list = []
for item in some_list:
some_list[:] = new_list

Notice the [:] on that last some_list -- it is causing a mutation of some_list's elements (setting the entire thing to new_list's elements) instead of rebinding the name some_list to new_list. Is this important? It depends! If you have other names besides some_list bound to the same list object, and you want them to see the updates, then you need to use the slicing method; if you don't, or if you do not want them to see the updates, then rebind -- some_list = new_list.

App installation failed due to application-identifier entitlement

This happened when I tried installing over top of an adhoc build.

How can I count the rows with data in an Excel sheet?

You should use the sumif function in Excel:


This function takes a range like this square A5:C10 then you have some text to find this text can be in A or B then it will add the number from the C-row.

Restricting input to textbox: allowing only numbers and decimal point

I observed that for all the answers provided here, the things are not working if we select some portion of the text in textbox and try to overwrite that part. So I modified the function which is as below:

    <SCRIPT language=Javascript>
       function isNumberKey(evt)
         var charCode = (evt.which) ? evt.which : event.keyCode;

if (charCode != 46 && charCode > 31 && (charCode < 48 || charCode > 57))
        return false;
 if (charCode == 46 && evt.srcElement.value.split('.').length>1 )

        return false;


          return true;

  if(evt.srcElement.value.split('.').length>1 && evt.srcElement.value.split('.')[1].length==2)

     return false;

    return true;

    <INPUT id="txtChar" onkeypress="return isNumberKey(event)" 
           type="text" name="txtChar">

Strange PostgreSQL "value too long for type character varying(500)"

Character varying is different than text. Try running

ALTER TABLE product_product ALTER COLUMN code TYPE text;

That will change the column type to text, which is limited to some very large amount of data (you would probably never actually hit it.)

How to run a script at a certain time on Linux?

Cron is good for something that will run periodically, like every Saturday at 4am. There's also anacron, which works around power shutdowns, sleeps, and whatnot. As well as at.

But for a one-off solution, that doesn't require root or anything, you can just use date to compute the seconds-since-epoch of the target time as well as the present time, then use expr to find the difference, and sleep that many seconds.

Strip double quotes from a string in .NET

I didn't see my thoughts repeated already, so I will suggest that you look at string.Trim in the Microsoft documentation for C# you can add a character to be trimmed instead of simply trimming empty spaces:

string withQuotes = "\"hellow\"";
string withOutQotes = withQuotes.Trim('"');

should result in withOutQuotes being "hello" instead of ""hello""

What is the difference between `` and `Enum.toString()`?

Use toString() when you want to present information to a user (including a developer looking at a log). Never rely in your code on toString() giving a specific value. Never test it against a specific string. If your code breaks when someone correctly changes the toString() return, then it was already broken.

If you need to get the exact name used to declare the enum constant, you should use name() as toString may have been overridden.

HTML <input type='file'> File Selection Event

jQuery way:

$('input[name=myInputName]').change(function(ev) {

    // your code

Stretch Image to Fit 100% of Div Height and Width

will the height attribute stretch the image beyond its native resolution? If I have a image with a height of say 420 pixels, I can't get css to stretch the image beyond the native resolution to fill the height of the viewport.

I am getting pretty close results with:

 .rightdiv img {
        max-width: 25vw;
        min-height: 100vh;

the 100vh is getting pretty close, with just a few pixels left over at the bottom for some reason.

How do I calculate tables size in Oracle

I modified the WW's query to provide more detailed information:

    owner, object_name, object_type, table_name, ROUND(bytes)/1024/1024 AS meg,
    tablespace_name, extents, initial_extent,
    ROUND(Sum(bytes/1024/1024) OVER (PARTITION BY table_name)) AS total_table_meg
  FROM (
    -- Tables
    SELECT owner, segment_name AS object_name, 'TABLE' AS object_type,
          segment_name AS table_name, bytes,
          tablespace_name, extents, initial_extent
    FROM   dba_segments
    -- Indexes
    SELECT i.owner, i.index_name AS object_name, 'INDEX' AS object_type,
          i.table_name, s.bytes,
          s.tablespace_name, s.extents, s.initial_extent
    FROM   dba_indexes i, dba_segments s
    WHERE  s.segment_name = i.index_name
    AND    s.owner = i.owner
    -- LOB Segments
    SELECT l.owner, l.column_name AS object_name, 'LOB_COLUMN' AS object_type,
          l.table_name, s.bytes,
          s.tablespace_name, s.extents, s.initial_extent
    FROM   dba_lobs l, dba_segments s
    WHERE  s.segment_name = l.segment_name
    AND    s.owner = l.owner
    AND    s.segment_type = 'LOBSEGMENT'
    -- LOB Indexes
    SELECT l.owner, l.column_name AS object_name, 'LOB_INDEX' AS object_type,
          l.table_name, s.bytes,
          s.tablespace_name, s.extents, s.initial_extent
    FROM   dba_lobs l, dba_segments s
    WHERE  s.segment_name = l.index_name
    AND    s.owner = l.owner
    AND    s.segment_type = 'LOBINDEX'
  WHERE owner = UPPER('&owner')
WHERE total_table_meg > 10
ORDER BY total_table_meg DESC, meg DESC

Where do I put a single filter that filters methods in two controllers in Rails

Two ways.

i. You can put it in ApplicationController and add the filters in the controller

    class ApplicationController < ActionController::Base       def filter_method       end     end      class FirstController < ApplicationController       before_filter :filter_method     end      class SecondController < ApplicationController       before_filter :filter_method     end 

But the problem here is that this method will be added to all the controllers since all of them extend from application controller

ii. Create a parent controller and define it there

 class ParentController < ApplicationController   def filter_method   end  end  class FirstController < ParentController   before_filter :filter_method end  class SecondController < ParentController   before_filter :filter_method end 

I have named it as parent controller but you can come up with a name that fits your situation properly.

You can also define the filter method in a module and include it in the controllers where you need the filter

Can I get JSON to load into an OrderedDict?

In addition to dumping the ordered list of keys alongside the dictionary, another low-tech solution, which has the advantage of being explicit, is to dump the (ordered) list of key-value pairs ordered_dict.items(); loading is a simple OrderedDict(<list of key-value pairs>). This handles an ordered dictionary despite the fact that JSON does not have this concept (JSON dictionaries have no order).

It is indeed nice to take advantage of the fact that json dumps the OrderedDict in the correct order. However, it is in general unnecessarily heavy and not necessarily meaningful to have to read all JSON dictionaries as an OrderedDict (through the object_pairs_hook argument), so an explicit conversion of only the dictionaries that must be ordered makes sense too.

Use JAXB to create Object from XML String

If you want to parse using InputStreams

public Object xmlToObject(String xmlDataString) {
        Object converted = null;
        try {
            JAXBContext jc = JAXBContext.newInstance(Response.class);
            Unmarshaller unmarshaller = jc.createUnmarshaller();
            InputStream stream = new ByteArrayInputStream(xmlDataString.getBytes(StandardCharsets.UTF_8));
            converted = unmarshaller.unmarshal(stream);
        } catch (JAXBException e) {
        return converted;

Set date input field's max date to today

it can be useful : If you want to do it with Symfony forms :

 $today = new DateTime('now');
 $formBuilder->add('startDate', DateType::class, array(
                   'widget' => 'single_text',
                   'data'   => new \DateTime(),
                   'attr'   => ['min' => $today->format('Y-m-d')]

How to check if a column exists in a datatable

It is much more accurate to use IndexOf:

If dt.Columns.IndexOf("ColumnName") = -1 Then
    'Column not exist
End If

If the Contains is used it would not differentiate between ColumName and ColumnName2.

How can I hide or encrypt JavaScript code?

The only safe way to protect your code is not giving it away. With client deployment, there is no avoiding the client having access to the code.

So the short answer is: You can't do it

The longer answer is considering flash or Silverlight. Although I believe silverlight will gladly give away it's secrets with reflector running on the client.

I'm not sure if something simular exists with the flash platform.

Restrict SQL Server Login access to only one database

  1. Connect to your SQL server instance using management studio
  2. Goto Security -> Logins -> (RIGHT CLICK) New Login
  3. fill in user details
  4. Under User Mapping, select the databases you want the user to be able to access and configure


You'll also want to goto Security -> Server Roles, and for public check the permissions for TSQL Default TCP/TSQL Default VIA/TSQL Local Machine/TSQL Named Pipesand remove the connect permission

How to use order by with union all in sql?

Select 'Shambhu' as ShambhuNewsFeed,Note as [News Fedd],NotificationId
from Notification with(nolock) where DesignationId=@Designation 
Union All 
Select 'Shambhu' as ShambhuNewsFeed,Note as [Notification],NotificationId
from Notification with(nolock) 
where DesignationId=@Designation 
order by NotificationId desc

Regex to check whether a string contains only numbers

\d will not match the decimal point. Use the following for the decimal.

const re = /^\d*(\.\d+)?$/
'123'.match(re)       // true
'123.3'.match(re)     // true
'123!3'.match(re)     // false

Error: Specified cast is not valid. (SqlManagerUI)

There are some funnies restoring old databases into SQL 2008 via the guy; have you tried doing it via TSQL ?

Use Master
FROM DISK = 'C:\YourBackUpFile.bak'
WITH MOVE 'YourMDFLogicalName' TO 'D:\Data\YourMDFFile.mdf',--check and adjust path
MOVE 'YourLDFLogicalName' TO 'D:\Data\YourLDFFile.ldf' 

Better way to check variable for null or empty string?

There is no better way but since it's an operation you usually do quite often, you'd better automatize the process.

Most frameworks offer a way to make arguments parsing an easy task. You can build you own object for that. Quick and dirty example :

class Request

    // This is the spirit but you may want to make that cleaner :-)
    function get($key, $default=null, $from=null)
         if ($from) :
             if (isset(${'_'.$from}[$key]));
                return sanitize(${'_'.strtoupper($from)}[$key]); // didn't test that but it should work
             if isset($_REQUEST[$key])
                return sanitize($_REQUEST[$key]);

         return $default;

    // basics. Enforce it with filters according to your needs
    function sanitize($data)
          return addslashes(trim($data));

    // your rules here
    function isEmptyString($data)
        return (trim($data) === "" or $data === null);

    function exists($key) {}

    function setFlash($name, $value) {}



$request = new Request();
$question= $request->get('question', '', 'post');
print $request->isEmptyString($question);

Symfony use that kind of sugar massively.

But you are talking about more than that, with your "// Handle error here ". You are mixing 2 jobs : getting the data and processing it. This is not the same at all.

There are other mechanisms you can use to validate data. Again, frameworks can show you best pratices.

Create objects that represent the data of your form, then attach processses and fall back to it. It sounds far more work that hacking a quick PHP script (and it is the first time), but it's reusable, flexible, and much less error prone since form validation with usual PHP tends to quickly become spaguetti code.

Default value in Go's method

No, there is no way to specify defaults. I believer this is done on purpose to enhance readability, at the cost of a little more time (and, hopefully, thought) on the writer's end.

I think the proper approach to having a "default" is to have a new function which supplies that default to the more generic function. Having this, your code becomes clearer on your intent. For example:

func SaySomething(say string) {
    // All the complicated bits involved in saying something

func SayHello() {

With very little effort, I made a function that does a common thing and reused the generic function. You can see this in many libraries, fmt.Println for example just adds a newline to what fmt.Print would otherwise do. When reading someone's code, however, it is clear what they intend to do by the function they call. With default values, I won't know what is supposed to be happening without also going to the function to reference what the default value actually is.

How can I group by date time column without taking time into consideration

In pre Sql 2008 By taking out the date part:

GROUP BY CONVERT(CHAR(8),DateTimeColumn,10)

"Series objects are mutable and cannot be hashed" error

Shortly: gene_name[x] is a mutable object so it cannot be hashed. To use an object as a key in a dictionary, python needs to use its hash value, and that's why you get an error.

Further explanation:

Mutable objects are objects which value can be changed. For example, list is a mutable object, since you can append to it. int is an immutable object, because you can't change it. When you do:

a = 5;
a = 3;

You don't change the value of a, you create a new object and make a point to its value.

Mutable objects cannot be hashed. See this answer.

To solve your problem, you should use immutable objects as keys in your dictionary. For example: tuple, string, int.

Passing Objects By Reference or Value in C#

In Pass By Reference You only add "ref" in the function parameters and one more thing you should be declaring function "static" because of main is static(#public void main(String[] args))!

namespace preparation
  public  class Program
      public static void swap(ref int lhs,ref int rhs)
          int temp = lhs;
          lhs = rhs;
          rhs = temp;
          static void Main(string[] args)
            int a = 10;
            int b = 80;

  Console.WriteLine("a is before sort " + a);
            Console.WriteLine("b is before sort " + b);
            swap(ref a, ref b);
            Console.WriteLine("a is after sort " + a);
            Console.WriteLine("b is after sort " + b);  

Calling Python in PHP

The backquote operator will also allow you to run python scripts using similar syntax to above

In a python file called

hello = "hello"
world = "world"
print hello + " " + world

In a php file called python.php:

$python = `python`;
echo $python;

Get screen width and height in Android

DisplayMetrics displayMetrics = new DisplayMetrics();
int height = displayMetrics.heightPixels;
int width = displayMetrics.widthPixels;

this may be not work in some case. for the getMetrics comments:

Gets display metrics that describe the size and density of this display. The size returned by this method does not necessarily represent the actual raw size (native resolution) of the display.

  1. The returned size may be adjusted to exclude certain system decor elements that are always visible.

  2. It may be scaled to provide compatibility with older applications that were originally designed for smaller displays.

  3. It can be different depending on the WindowManager to which the display belongs.

  • If requested from non-Activity context (e.g. Application context via (WindowManager) getApplicationContext().getSystemService(Context.WINDOW_SERVICE)) metrics will report the size of the entire display based on current rotation and with subtracted system decoration areas.

  • If requested from activity (either using getWindowManager() or (WindowManager) getSystemService(Context.WINDOW_SERVICE)) resulting metrics will correspond to current app window metrics. In this case the size can be smaller than physical size in multi-window mode.

So, to get the real size:

DisplayMetrics displayMetrics = new DisplayMetrics();
int height = displayMetrics.heightPixels;
int width = displayMetrics.widthPixels;


Point point = new Point();
int height = point.y;
int width = point.x;

How to make pylab.savefig() save image for 'maximized' window instead of default size

You can look in a saved figure it's size, like 1920x983 px (size when i saved a maximized window), then I set the dpi as 100 and the size as 19.20x9.83 and it worked fine. Saved exactly equal to the maximized figure.

import numpy as np
import matplotlib.pyplot as plt
x, y = np.genfromtxt('fname.dat', usecols=(0,1), unpack=True)
a = plt.figure(figsize=(19.20,9.83))
a = plt.plot(x, y, '-')

Disable / Check for Mock Location (prevent gps spoofing)

You can add additional check based on cell tower triangulation or Wifi Access Points info using Google Maps Geolocation API

The simplest way to get info about CellTowers

final TelephonyManager telephonyManager = (TelephonyManager) appContext.getSystemService(Context.TELEPHONY_SERVICE);
String networkOperator = telephonyManager.getNetworkOperator();
int mcc = Integer.parseInt(networkOperator.substring(0, 3));
int mnc = Integer.parseInt(networkOperator.substring(3));
String operatorName = telephonyManager.getNetworkOperatorName();
final GsmCellLocation cellLocation = (GsmCellLocation) telephonyManager.getCellLocation();
int cid = cellLocation.getCid();
int lac = cellLocation.getLac();

You can compare your results with site

To get info about Wifi Access Points

final WifiManager mWifiManager = (WifiManager) appContext.getApplicationContext().getSystemService(Context.WIFI_SERVICE);

if (mWifiManager != null && mWifiManager.getWifiState() == WifiManager.WIFI_STATE_ENABLED) {

    // register WiFi scan results receiver
    IntentFilter filter = new IntentFilter();

    BroadcastReceiver broadcastReceiver = new BroadcastReceiver() {
            public void onReceive(Context context, Intent intent) {
                List<ScanResult> results = mWifiManager.getScanResults();//<-result list

        appContext.registerReceiver(broadcastReceiver, filter);

        // start WiFi Scan

Nothing was returned from render. This usually means a return statement is missing. Or, to render nothing, return null

Got the answer: I should not use parentheses after return (). This works:

return  <div> <Search_Bar /> </div>

If you want to write multiline, then return ( ...

Your starting parenthesis should be on the same line as return.

How do I get an animated gif to work in WPF?

I, too, did a search and found several different solution in just a thread on the old MSDN forums. (link no longer worked so I removed it)

The simplest to execute seems to be to use a WinForms PictureBox control, and went like this (changed a few things from the thread, most of it the same).

Add a reference to System.Windows.Forms, WindowsFormsIntegration, and System.Drawing to your project first.

<Window x:Class="GifExample.Window1"
    Loaded="Window_Loaded" >
            <winForms:PictureBox x:Name="pictureBoxLoading">
</Window >

Then in the Window_Loaded handler, you would set the pictureBoxLoading.ImageLocation property to the image file path that you want to show.

private void Window_Loaded(object sender, RoutedEventArgs e)
    pictureBoxLoading.ImageLocation = "../Images/mygif.gif";

The MediaElement control was mentioned in that thread, but it is also mentioned that it is a rather heavy control, so there were a number of alternatives, including at least 2 homebrewed controls based on the Image control, so this is the simplest.

Android Emulator sdcard push error: Read-only file system

Alternate way: Dismount the drive (from settings/storage) and re-mount the sdcard also fixes the problem. (verify by moving a file from internal storage to sdcard) In any case, this simple method saved my butt this time :)

Insert multiple rows WITHOUT repeating the "INSERT INTO ..." part of the statement?

I've been using the following:

INSERT INTO [TableName] (ID, Name)
values (NEWID(), NEWID())
GO 10

It will add ten rows with unique GUIDs for ID and Name.

Note: do not end the last line (GO 10) with ';' because it will throw error: A fatal scripting error occurred. Incorrect syntax was encountered while parsing GO.

Maximum call stack size exceeded error

Sometimes happened because of convert data type , for example you have an object that you considered as string. in nodejs either in js client as example, is not a string. to use it as string you have to add the word String before:


how to create virtual host on XAMPP

Step 1) Open Host File Under "C:\Windows\System32\drivers\etc"


Step 2) Open httpd-vhosts.conf File Under "C:\xampp\apache\conf\extra"


    DocumentRoot "C:/xampp/htdocs/vipnum/"
    SetEnv APPLICATION_ENV "development"
    <Directory "C:/xampp/htdocs/vipnum/">
        DirectoryIndex index.php
        AllowOverride All
        Order allow,deny
        Allow from all

pythonw.exe or python.exe?

See here:

pythonw.exe "This suppresses the terminal window on startup."

Trim Cells using VBA in Excel

If you have a non-printing character at the front of the string try this

Option Explicit
Sub DoTrim()
    Dim cell As Range
    Dim str As String
    Dim nAscii As Integer
    For Each cell In Selection.Cells
        If cell.HasFormula = False Then
            str = Trim(CStr(cell))
            If Len(str) > 0 Then
                nAscii = Asc(Left(str, 1))
                If nAscii < 33 Or nAscii = 160 Then
                    If Len(str) > 1 Then
                        str = Right(str, Len(str) - 1)
                        strl = ""
                    End If
                End If
            End If
        End If
End Sub

Can Windows Containers be hosted on linux?

Update3: 06.2019 Some of the comments says that the answer is not clear, I'll try to clarify.


Q: Can Windows containers run on Linux?

A: No. They cannot. Containers are using the underlying Operating System resources and drivers, so Windows containers can run on Windows only, and Linux containers can run on Linux only.

Q: But what about Docker for Windows? Or other VM-based solutions?

A: Docker for Windows allows you to simulate running Linux containers on Windows, but under the hood a Linux VM is created, so still Linux containers are running on Linux, and Windows containers are running on Windows.

Bonus: Read this very nice article about running Linux docker containers on Windows.

Q: So, what should I do with a .Net Framework 462 app, if I would like to run in a container?

A: It depends. Following several recommendations:

  • If it is possible - move to .Net Core. Since .Net Core brings support to most major features of .Net Framework, and .Net Framework 4.8 will be the last version of .Net framework
  • If you cannot migrate to .Net Core - As @Sebastian mentioned - you can convert your libraries to .Net Standard, and have 2 versions of app - one on .Net Framework 4.6.2, and one on .Net Core - it is not always obvious, Visual Studio supports it pretty well (with multi-targeting), but some dependencies can require extra care.

  • (Less recommended) In some cases, you can run windows containers. Windows containers are becoming more and more mature, with better support in platforms like Kubernetes. But to be able to run .Net Framework code, you still need to run on base image of "Server Core", which occupies about 1.4 GB. In same rare cases, you can migrate your code to .Net Core, but still run on Windows Nano servers, with an image size of 95 MB.

Leaving also the old updates for history

Update2: 08.2018 If you are using Docker-for-Windows, you can run now both windows and linux containers simultaneously:

Bonus: Not directly related to the question, but you can now run not only the linux container itself, but also orchestrator like kubernetes:

Updated at 2018:

Original answer in general is right, BUT several months ago, docker added experimental feature LCOW (official github repository).

From this post:

Doesn’t Docker for Windows already run Linux containers? That’s right. Docker for Windows can run Linux or Windows containers, with support for Linux containers via a Hyper-V Moby Linux VM (as of Docker for Windows 17.10 this VM is based on LinuxKit).

The setup for running Linux containers with LCOW is a lot simpler than the previous architecture where a Hyper-V Linux VM runs a Linux Docker daemon, along with all your containers. With LCOW, the Docker daemon runs as a Windows process (same as when running Docker Windows containers), and every time you start a Linux container Docker launches a minimal Hyper-V hypervisor running a VM with a Linux kernel, runc and the container processes running on top.

Because there’s only one Docker daemon, and because that daemon now runs on Windows, it will soon be possible to run Windows and Linux Docker containers side-by-side, in the same networking namespace. This will unlock a lot of exciting development and production scenarios for Docker users on Windows.


As mentioned in comments by @PanagiotisKanavos, containers are not for virtualization, and they are using the resources of the host machine. As a result, for now windows container cannot run "as-is" on linux machine.

But - you can do it by using VM - as it works on windows. You can install windows VM on your linux host, which will allow to run windows containers.

With it, IMHO run it this way on PROD environment will not be the best idea.

Also, this answer provides more details.

How to set cache: false in jQuery.get call

To me, the correct way of doing it would be the ones listed. Either ajax or ajaxSetup. If you really want to use get and not use ajaxSetup then you could create your own parameter and give it the value of the the current date/time.

I would however question your motives in not using one of the other methods.

How to use MySQL dump from a remote machine

Tried all the combinations here, but this worked for me:

mysqldump -u root -p --default-character-set=utf8mb4 [DATABASE TO BE COPIED NAME] > [NEW DATABASE NAME]

How can I delete a user in linux when the system says its currently used in a process

First use pkill or kill -9 <pid> to kill the process.

Then use following userdel command to delete user,

userdel -f cafe_fixer

According to userdel man page:

-f, --force

This option forces the removal of the user account, even if the user is still logged in. It also forces userdel to remove the user's home directory and mail spool, even if another user uses the same home directory or if the mail spool is not owned by the specified user. If USERGROUPS_ENAB is defined to yes in /etc/login.defs and if a group exists with the same name as the deleted user, then this group will be removed, even if it is still the primary group of another user.

Edit 1: (by @Ajedi32)

Note: This option (i.e. --force) is dangerous and may leave your system in an inconsistent state.

Edit 2: (by @socketpair)

In spite of the description about some files, this key allows removing the user while it is in use. Don't forget to chdir / before, because this command will also remove home directory.

SELECT using 'CASE' in SQL

which platform ?

   END AS FRUIT     

How do I set the proxy to be used by the JVM

You can set those flags programmatically this way:

if (needsProxy()) {
} else {

Just return the right values from the methods needsProxy(), getProxyHost() and getProxyPort() and you can call this code snippet whenever you want.

MySQL - force not to use cache for testing speed of query

If you want to disable the Query cache set the 'query_cache_size' to 0 in your mysql configuration file . If its set 0 mysql wont use the query cache.

How to get all selected values of a multiple select box?


[].filter(option => option.selected).map(option => option.value)

Where select is a reference to the <select> element.

To break it down:

  • [] takes the Array-like list of options and destructures it so that we can use Array.prototype methods on it (Edit: also consider using Array.from())
  • filter(...) reduces the options to only the ones that are selected
  • map(...) converts the raw <option> elements into their respective values